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Ion Information and Elemental Patterns. Chapter 6 (Hoffmann & Stroobant) Chapter 1 (Johnstone and Rose, 1996). Two Main Facets of Mass Spectrometry. Compared with most other common methods of physicochemical spectroscopic analysis, some or all of the samples is consumed. - PowerPoint PPT Presentation
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1
Ion Information and Elemental Patterns
Chapter 6 (Hoffmann amp Stroobant)
Chapter 1 (Johnstone and Rose 1996)
2
Two Main Facets of Mass Spectrometry
bull Compared with most other common methods of physicochemical spectroscopic analysis some or all of the samples is consumed
bull MS does not deal with a well-defined property of a molecule The appearance of a mass spectrum depends on the compounds itself but also upon the interval of time between ionization and detection initial energy distribution in the molecule ionization method etchellip
3
MS Spectral Collections and Database
bull NISTEPANIH gt190000 spectra (over 163000 compounds)
bull Wiley Registry of Mass Spectral Data 380000 spectra (over 200000 compounds)
bull Eight-Peak Index of Mass Spectra 81000 spectra (over 65000 compounds)
4
5
RICUsed when
background and unwanted impurities
are removed
RA is affected by the error in
measuring base peak
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
2
Two Main Facets of Mass Spectrometry
bull Compared with most other common methods of physicochemical spectroscopic analysis some or all of the samples is consumed
bull MS does not deal with a well-defined property of a molecule The appearance of a mass spectrum depends on the compounds itself but also upon the interval of time between ionization and detection initial energy distribution in the molecule ionization method etchellip
3
MS Spectral Collections and Database
bull NISTEPANIH gt190000 spectra (over 163000 compounds)
bull Wiley Registry of Mass Spectral Data 380000 spectra (over 200000 compounds)
bull Eight-Peak Index of Mass Spectra 81000 spectra (over 65000 compounds)
4
5
RICUsed when
background and unwanted impurities
are removed
RA is affected by the error in
measuring base peak
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
3
MS Spectral Collections and Database
bull NISTEPANIH gt190000 spectra (over 163000 compounds)
bull Wiley Registry of Mass Spectral Data 380000 spectra (over 200000 compounds)
bull Eight-Peak Index of Mass Spectra 81000 spectra (over 65000 compounds)
4
5
RICUsed when
background and unwanted impurities
are removed
RA is affected by the error in
measuring base peak
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
4
5
RICUsed when
background and unwanted impurities
are removed
RA is affected by the error in
measuring base peak
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
5
RICUsed when
background and unwanted impurities
are removed
RA is affected by the error in
measuring base peak
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
6
Multiply Charged Ions
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
7
bull The ions in a mass spectrometer that have sufficient energy to fragment sometime after leaving the ion source but before arriving at the detector
bull M+ A+ + N
(m1z) (m2z) (m1-m2)
1 M+ with large amount of internal energy will fragment in the ionization source producing ldquonormalrdquo A+ ions These A+ ions will be seen as narrow peaks at mz values correct for the mass and charge on the ion A+
2 M+ having only a small excess of internal energy reach detector before decomposition can occur Narrow peaks for ldquonormalrdquo M+ appear
3 M+ which posses excesses of internal energy that are in between the those in above two cases may fragment after leaving the ion source and before reaching the detector The product ions A+ are seen in the mass spectrum as broad peaks centered at mz values that are nor correct for the mass and charge on the ion A+
Metastable ions
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
8
bull These broad peaks are called ldquometastable ion peaksrdquo
bull These ldquoldquometastable ion peaksrdquo do not represent metastable M+ ions but represent products of decomposition of metastable ions
bull The cause of A+ ions from metastable ion decomposition being detected differently form ldquonormalrdquo A+ ions is due to their different momenta
Metastable ions
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
9
Metastable Ions
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
10
93
66
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
11
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
12
Just for clarification
Atomic massamu atomic mass units (uma)ldquoDardquo or Dalton kD (kiloDalton) 1 amu = 16605610
-27
kg proton mp = 16726510
-27
kg neutron mn = 16749510
-27
kg
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
13
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
14
Exact Masses of Some Common Elements and Their Isotopes
Element Symbol Exact Mass (u) Rel Abundance
Hydrogen 1H 1007825037 1000
Deuterium 2H or D
2014101787 0015
Carbon 12 12C 1200000 1000
Carbon 13 13C 13003354 111223
Nitrogen 14 14N 14003074 1000
Nitrogen 15 15N 1500011 036734
Oxygen 16 16O 1599491464 1000
Oxygen 17 17O 169991306 003809
Oxygen 18 18O 1799915939 020048
Fluorine 19F 18998405 1000
Sodium 23Na 229897697 1000
Silicon 28 28Si 279769284 9223
Silicon 29 29Si 289764964 50634
Silicon 30 30Si 299737717 33612
Phosphorus 31P 309737634 1000
Sulfur 32 32S 31972074 1000
Sulfur 33 33S 329707 078931
Sulfur 34 34S 3396938 443065
Sulfur 36 36S 3596676 002105
Chlorine 35 35Cl 34968854 1000
Chlorine 37 37Cl 36965896 3197836
See Table 4A for more elements
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
15
Isotopic peaks
bull Mass spectrum of methane CH4
mz =16 (12CH4) and mz = 17 (13CH4)
relative abundance = 991
bull For a compound with 10 carbons (C10H18)
The chance of incorporating one 13C into the molecule will be 10 times more Therefore [M+1]+ would be 10 x108 = 108 percent of the abundance of [M]+ (see slide 5)
bull For a compound with 10 carbons the approximate relative heights of the [M]+ [M+1]+ [M+2]+ and [M+3]+ peaks are 10010045001
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
16
Isotopic Peaks
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
17
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
18
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
19
(a) only one chlorine atom (b) only one bromine atom
c) one chlorine and one bromine atom
31 11
341
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
20
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
21
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
22
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
23
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
24
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
25
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
26
Molecular ions
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
27
Normalized Mass Spectra
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
28
Normalized Mass Spectra
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
29
Directly Recorded Mass Spectra
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
30
Computerized Mass Spectra
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
31
Accurate mass determination to several decimal places using a doublendashfocusing mass spectrometer enables the determination of molecular formulae and elemental compositions
High Resolution Accurate Mass Measurement Elemental Compositions
For an ion of NH3 the measured integer mass would be 17 viz mz = 171 = 17 for z = 1
In theory this process can be reversed in that any measured mass leads to an elemental composition
bull For example a measured value of 17 would imply the composition NH3
bull In practice there are other elemental compositions which could add up to 17 For example OH (oxygen = 16 hydrogen = 1) CD2H (carbon = 12 deuterium = 22 hydrogen = 1)
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
32
High Resolution Accurate Mass Measurement Elemental Compositions
For larger masses the possibilities increase enormously
ndash At mass 100 there would be literally thousands of possible elemental compositions unit mass is not enough
bull In fact atomic masses are not integers
ndash C = 120000 ndash O = 159949 ndash N = 140031 ndash H = 10078 and so onhellip
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265 The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are potentially separable
A mass spectrometer which can measure mass correct to several decimal places rather than just integer mass can be used to measure such differences RESOLUTION IS IMPORTANT ELEMENTAL ANALYSIS
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
33
mz measured5804189
C3H6O
Accurate Mass Determination
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
34
Exact masses and corresponding formulae for various possible ions of mz 180 containing only carbon hydrogen nitrogen and oxygen atoms in
limited number (C6-15 H0-24 N0-4 and O0-4)
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
35
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
36
What is mass resolution
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
37
The accurate mass for ammonia (NH3 ) is 140031 + 3 x 10078 = 170265
The accurate mass of OH is 159949 + 10078 = 170027
giving a mass difference of 00238 units between NH3 and OH which are
potentially separable
m = 00238 amu
m= 170265 amu for NH3
Minimum resolution required
R = 17026500238 = 7154
Lets go back to resolution what do I need to separate them
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
38
How good is good
5000 resolution separate mz 50000 from mz 50010
mz 10000 from mz 10002
mz 10000 from mz 10002
mz 10000 from mz 10002
Unit resolution mz 50 from mz 51
mz 100 from mz 101
mz 1000 from mz 1001
H
h
(hH)x100 le 10
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
39
500 10000
Clenbuterol mz 355
40
Sensitivity vs selectivity
When resolution is not a good thing
41
40
Sensitivity vs selectivity
When resolution is not a good thing
41
41
