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Roger L Firor
Agilent Technologies
Wilmington, DE
Low Thermal Mass (LTM) GC
Technology Revealed: A Practical
Guide
Page 1
Gulf Coast Conference 2011
Gulf Coast Conference 2011
“LTM” (Low Thermal Mass) Technology (Patented)
Directly heat/cool fused silica GC columns
Page 2
LTM - Low Thermal Mass Technology
3
“Fast Temperature Ramps”
“Spec” 1800oC/min, Typical <400oC/min
Temperature Range 120 V Oven Fast Ramps Insert **
(°C) (°C/min) > 200 V, 15A > 200 V, 15A
50 to 70 75 120 120
70 to 115 45 95 120
115 to 175 40 65 110
175 to 300 30 45 80
300 to 450 20 35 65
* * Requires G2646-60500
LTM Cooldown Times (Standard Size)
0
50
100
150
200
250
300
350
400
0 50 100 150 200 250
Time (sec)
Tem
p (
oC
) 2m LTM
5m LTM
10m LTM
7890 GC
“Fast Cool-Down”
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LTM Column Module
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Lead
Torus Lead
FANS
Installed external to main GC oven
Connecting an LTM Column Module to Inlet and
Detector
• Option 1: Use CFT unions and deactivated fused silica leads
of same diameter as column
> Column module protected by retention gap tubing
> Users need to learn how to make CFT connections
• Option 2: Use module with long column leads
> Avoids use of unions
> 0.5 to 0.8 m of column is kept at elevated temperature
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Module to Retention Gap Connection
Old New
2010: Valco Unions Unions Based on Capillary
Flow Technology (CFT)
Metal Ferrules Easy to use, do not loosen or leak
with oven cycling to 350 C
Metal Deactivation
Page 7
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Transfer Line Assembly
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Heated column guide
Brackets attach to rails
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5 inch Column Module Installed on Transfer line
2011: LTM II
LTM Integrated w/ 7890 GC
- Hardware
- Firmware
- Software
Page 10
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LTM II: Electronics/Firmware Integration
LTM PCB – Direct digital communication
w/ 7890 GC FW/UI:
- PCB has “GC” performance/reliability
- Improved thermal control (now digital).
Temperature control/display
- Confirms cable connections
- Diagnostics, thermal fault detection
- Added “GC” Press/Flow compensations
multi-piece columns (knows temp)
- Local control via 7890 keyboard
- LTM integrated into GC, GC/MS SW platforms
Page 11
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LTM Series II IN Segment Out Segment Segment 2
GC Oven GC Oven MSD
Column Segment
Configuring an LTM II Module in ChemStation
12
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GC Oven is set isothermal at a temperature at or close to maximum
LTM module programmed temperature
What are the Best Uses for LTM Technology?
• Speed up an analysis where overall throughput is important
> Simulated Distillation
> Total Petroleum Hydrocarbons
> Solvent analysis
• Multi-dimensional separations where an independent oven is
needed to operate under a different temperature program
compared to the main GC oven
>Residual sulfur in diesel
> Fuel Ethanol
> GC X GC
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The LTM Advantage
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• Total Cycle time for an analysis can be cut by a factor of
three or more (compared to same columns in an air oven)
• Single or dual column configurations (5 inch format)
• Dual column configurations allow simultaneous injection
• With dual column modules, two different phases (i.e. 624 and Wax) can be used
• Temperature programs for the two column modules are independent
Four modules possible with 3 inch format
• Simultaneous start times are required, however, end times can vary
• Compatible with CFT devices for splitting - two columns, or for backflush
• Powerful tool when combined with a CFT Deans switch
Setting Column Flow with an LTM Module (First
Generation)
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•The 7890A or 6890 Series GC’s did not have knowledge of LTM column
temperature
•Constant flow mode could not be set from the GC keypad or software
•Options for setting flow in an LTM Module - constant pressure
- ramped flow
For approximate constant flow-
- construct a flow ramp
- manually measure flow at staring and final temperature- input flow ramp
Setting Column Flow with an LTM Module (Second
Generation: LTM II)
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•The 7890A GC has knowledge of LTM column module temperature
•Constant flow mode integrated
•Options for setting flow in an LTM II Module > constant pressure
> constant flow
> ramped flow
•LTM II control completely integrated in GC ChemStation
•LTM II parameters can also be set from the 7890A keypad
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*Maximum program rate for 120V 7890A is 30 C/min from 35 °C to 240 °C
** Maximum program rate for 220V 7890A is 45 C/min from 35 °C to 240 °C
Comparison of Cycle Times: Conventional Air Bath vs. LTM
Heating Column Program Cool Down Cycle
Time
7890A (120V) 30M x 0.53mm x
3.0um DB624
40 C(20 min) to 240
C (20 min) @ 10
C/min
6 min 50 sec with
3 min oven equil. 67 min
7890A (120V) 7M x 0.25mm x
1.4um DB624
35 C (5 min) to 240
C (5 min) @ 30
C/min *
8 min 25 sec
with 3 min oven
equil.
25 min
15 sec
7890A
(220V)
7M x 0.25mm x
1.4um DB624
35 C (5 min) to
240 C (5 min) @ 45
C/min **
8 min with 3 min
oven equil. 22 min
30 sec
LTM (Fast) 7M x 0.25mm x
1.4um DB624
35 C (5 min) to 240
C (5 min) @ 60
C/min
1 min 45 sec (one
module system)
15 min
10 sec
LTM (Faster) 7M x 0.25mm x
1.4um DB624
35 C (5 min) to 240
C (3 min) @ 100
C/min
1 min 45 sec (one
module system) 11 min
45 sec
LTM (Fastest) 7M x 0.25mm x
1.4um DB624
35 C (4 min) to 240
C (3 min) @120
C/min
1 min 45 sec (one
module system) 10 min
30 sec
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Fast Chromatography
• Users typically choose columns that are longer than needed
for a given application
• Optimal oven program rates will be around 10 °C/void time
• Consider column flow rates that are 2 to 3 times optimum
• When translating a method from air-bath to LTM:
- consider changing both column ID and length
- use method translation software for guidance
• Rarely will practical LTM program rates exceed 400 °C/min
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Method Translate: Long to Short Column of Same
Diameter [column rows]
Flow Rate Column ID 10M 5M 4M
ml/min um (°C/min) (°C/min) (°C/min)
12 530 15 31 (2X) 40 (2.6X)
6 320 15 34 (2X) 44 (3X)
3 250 15 35 (2X) 45 (3X)
2 180 15 34 (2X) 50 (3X)
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Simplest Calculator: Agilent Pressure/Flow Typically used to find inlet pressure and/or flows
Lengths and diameters are found by iteration
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Agilent Method Translator Find conditions to get same elution order and precisely scale method to new speed or
new outlet pressure
New inlet pressure
New flow
Speed up factor
Constant phase ratio
Translation from 10M to 5M: D2887
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Column ID and Phase ratio maintained
Translation from 530 to 320
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320 column available with
1.50um film – close enough
Phase ratio maintained
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Translation to LTM: D2887 SimDis 530u to 320u column
Interfacing LTM II to a Deans Switch
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Deans Switch Calculator
Primary column: 1.3 ml/min, LTM: 2.5 ml/min
September 22, 2011 26
LTM Series II/ Deans Switch/5975C
System Diagram: LTM ll/Deans/FID-MSD
Primary column
30 m x 0.25 mm x 0.25 um DB5ms
2 1
3 NO
NC
Split
Inlet 5975C
MSD
LTM II
FID restrictor
PCM
Deans Switch
27
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7 m x 0.25 mm x 0.25 um
HP-INNOWax
System Diagram: LTM ll/Deans/FID-FID
Primary column
2 1
3 NO
NC
Split
Inlet
LTM II
FID restrictor
PCM
Deans Switch
FID
28
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4,6-Dimethyl dibenzothiophene in Road Diesel
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FID
SIM
TIC
7.2 ppm
Oven Programs
Primary: 80 °C (0) to 340 °C (5) @ 10 °C/min
LTM II: 50 °C (3) to 240 °C (5) @ 8 °C/min Ovens offset by 30° C
10.6 ppb 4,6-Dimethy dibenzothiophene
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SIM
Standard
1.8 ppm of 4,6-Dimethyl dibenzothiophene in
Marine Diesel
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FID
SIM
TIC
Calibration
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y = 125764x - 17928 R² = 0.9995
0
200000
400000
600000
800000
1000000
1200000
1400000
0 2 4 6 8 10 12
4,6-Dimethyldibenzothiophene
y = 91849x + 806.33 R² = 0.9999
0
20000
40000
60000
80000
100000
120000
0 0.2 0.4 0.6 0.8 1 1.2
ppm
ppm
Fuel Ethanol
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1 2
3 4
5 6
EtOH
1. Butane
2. Acetaldehyde
3. Iso-pentane
4. Pentane
5. 2-Pentene
6. Methanol
Methanol level is 0.01%
Primary oven: 50 °C (5 min) to 280 °C (5 min) @ 20 °C/min
LTM: 30 °C (4 min) to 240 °C (5 min) @ 8 °C/min
Cut: 1.80 min to 2.00 min
Primary oven: 30 m x 0.25 mm x 0.25 um DB-5ms
LTM: 7 m x 0.25 mm x 0.25 um INNOwax
Ovens offset by 20 °C
LTM II/Deans Switch for Analysis of Natural Oils
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Geranium, cuts at: 8.25 to 8.38
(linalool), 9.3 to 9.5 Methone),
10.0 to 10.9 ( citronellyl formate,
B-citronellol, nerol)
1
2
3
4
5
6
Primary column: 30 m x 0.25 mm x 0.25 um DB5ms
LTM II column: 30 m x 0.25 mm Cyclodex
Primary:70 °C (1) to 280 °C (17) @ 10 °C/min
LTM II: 75 °C (7) to 130 °C (5) @ 2 °C/min
Oven Programs
1. Linalool
2. Methone
3. Citronellolyl Formate
4. Citronellol
5. Cital
6. Nerol
Fast GC Applications
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Parameters: Hydrocarbon Oil Index
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Injection 1 µL, splitless (0.4 min purge delay), 350°C
Inlet liner split/splitless P/N 5183 - 4647
(bottom taper, glass wool near top, 4 mm i.d., )
Carrier gas 9 mL/min He constant flow
LTM Column 10 m x 0.32 mm i.d. x 0.1 µm DB-5HT
LTM Retention gap leads 0.5 m x 0.32 mm ID on inlet and detector sides
Standard oven program 40°C (0.5 min), 340°C (0.5 min) @ 15°C/min
[total run time = 21 min]
GC oven temp when using LTM II 340°C isothermal (3 min)
LTM II oven program 40°C (0.5 min), 200°C/min 240°C,
100°C/min 340°C (0.5 min) [total time = 3min]
C 10 to C40 alkane test mix: 0.001 min SD or 0.03% RSD
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Motor oil
Diesel
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
Time (min)
Re
sp
on
se
400 mg/L Calibration Sample of Diesel
Plus Motor Oil
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0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00
500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000
Resp
on
se
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00
500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000
Time (min)
Resp
on
se
LTM, 3 min run
Standard, 21 min run
Comparison of Sensitivity Gain from Standard
Oven Program to Fast LTM Program
Diesel plus motor oil standard at 400 mg/L.
D2887 SimDis
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5 m x 0.32 mm x 0.5 um DB1
LTM Module: 35°C to 350°C (30 s) @ 100°C/min
Multimode inlet: 325°C (0 min) to 355°C (2 min) @ 200°C/min
Constant Flow: 12 ml/min
Split: 20 to 1
7890A oven: 300°C
C5 to C40 Calibration in under 3 min.
RGO
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PW 500: LTM II System
0 1 2 3 4 5 6 7 8
Column: 5M x 0.53mm x 0.15um DB-HT SimDis
LTM Temp Program: 40°C (0 sec) to 400°C (30 sec) @ 50°C/min
7890A Oven: 325°C Isothermal
7890A Carrier: He, constant flow
Injection: 2 ul of PW500 in toluene
PTV: 210°C (0 min) to 400°C (2 min) @ 300°C/min
C20 C70
GCxGC: Dual LTM II System
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PCM: Pressure control mode,
S/S inlet:: constant flow mode
LTM columns in constant flow
Three Independent temperature programs possible
FID FID FID
Column 2
S/S Inlet
Column 1
PCM Micro Valve Modulator
S/S Inlet
Column 1
PCM Micro Valve Modulator
S/S Inlet
Column 1
PCM Micro Valve Modulator
FID FID FID
Column 3
FID FID LTM
FID FID LTM
FID FID
Splitter LTM = Low Thermal Mass
Dual LTM: DB17HT and INNOwax
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DB17HT
INNOwax
40 °C (0 min) to 200 °C @ 3 °C/min
5 m x 0.25 mm x 0.15 um
30 °C (5 min) to 240 °C @ 2 °C/min
5 m x 0.25 mm x 0.15 um
Paraffin/aromatic mix
•Faster method development
•Complimentary results
depending on application
•Allows wider range of columns
(phase ratio’s) to be used
•Greater separation power for
complex materials
LTM Series II
• System part # : G6680A, 5 inch format with 2 power supplies
• 7890A firmware requirement: A.01.12.1 or greater
• GC ChemStation: B.04.03 DSP1, includes LTM II control
software
• MSD ChemStation: E.02.02
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Summary
• LTM series II incorporates a number of new features including full control
integrated in ChemStation, and operation in true constant flow mode that
assists the analyst with development of new methods. This is especially true
with more complex configurations involving the Deans switch and 5975C
MSD.
• The use of two independent ovens gives the analyst flexibility to optimize
analysis by using unique oven programs with offset temperatures.
• In many applications, analysis time will also be shorter since only
compounds of interest are cut to the chiral column.
• High ramp rates and rapid cool down give faster overall cycle times.
• Method translation software should be used when developing a fast
method.
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Recommended