Principles and selected applications of Diffusion-Ordered NMR Spectroscopy Stéphane Viel, Ph. D....

Principles and selected applications of Principles and selected applications of Diffusion-Ordered NMR SpectroscopyDiffusion-Ordered NMR Spectroscopy

Stéphane Viel, Ph. D.Stéphane Viel, Ph. D.Assistant ProfessorAssistant Professor

Aix-Marseille UniversityAix-Marseille UniversityMolecular Sciences Institute II (UMR-6263)Molecular Sciences Institute II (UMR-6263)

Chemometrics and Spectroscopy LaboratoryChemometrics and Spectroscopy LaboratoryMarseilles (France)Marseilles (France)

1992 1996 2000 2004 2008

DOSY ?

Diffusion Ordered NMR Spectroscopy

Web of Science, 12 / 2007

1992 1996 2000 2004 2008

DOSY ?

Diffusion Ordered NMR Spectroscopy

Web of Science, 12 / 2007

NMR and Diffusion…NMR and Diffusion…

19501950

19541954

PGSEPulsed Gradient Spin Echo19651965

19811981

19871987

DOSYDiffusion Ordered SpectroscopY

19921992

DOSYDiffusion Ordered SpectroscopY

19921992

PGSEPulsed Gradient Spin Echo19651965

General outlineGeneral outline

• Part 1: Theory about molecular mobility

– Self-diffusion– Study of self-diffusion by NMR

• Principles of Pulsed Gradient Spin Echo (PGSE)• Diffusion ordered NMR spectroscopy (DOSY)

• Part 2: Selected applications of DOSY

Self-diffusionSelf-diffusion

• Random translational motion of molecules or ions that arises from the thermal energy under conditions of thermodynamic equilibrium– No thermal gradient (convection)– No concentration gradient (mutual diffusion)

self-diffusion coefficient

root mean square displacement

Self-diffusion by Brown, 1828Self-diffusion by Brown, 1828

time = time = tt

stime = 0time = 0

• « Random jostling of molecules which leads to their net displacement over time »

tDns 2

•D self-diffusion coefficient

•k Boltzmann’s constant

•T absolute temperature

•f friction factorf

Self-diffusion coefficient Self-diffusion coefficient DD

• DD is related to the hydrodynamic volume of the diffusing particle through

11af 6

Self-diffusion coefficient Self-diffusion coefficient DD

• DD is related to the hydrodynamic volume of the diffusing particle through

•D self-diffusion coefficient

•k Boltzmann’s constant

•T absolute temperature

•f friction factor

Sphere

• For a sphere diffusing in an isotropic and continuous medium of viscosity :

Stokes Einstein equationStokes Einstein equation

Diffusion Molecular Size

• PPulsed GGradient SSpin EEcho (PGSEPGSE)– Stejskal and Tanner, 1965– Gradients of magnetic field (Pulsed)

Study of self-diffusion by NMRStudy of self-diffusion by NMR

GradientPulses

OFF OFF OFF OFF

ON ON ON

1. Spatially label the nuclear spins using

gradients of magnetic field.

Study of self-diffusion by NMRStudy of self-diffusion by NMR

2. Monitor their displacement by measuring

their spatial positions at 2 distinct times.

Principle: 2 steps

Nuclear magnetogyric ratio

Larmor frequencyLarmor frequency

In NMR, each nuclear spin is identified by its Larmor precession frequency 0

B0 00 B

Magnetic field gradientMagnetic field gradient

Magnetic field gradient

Spatially dependentmagnetic field

For a single and constant gradient oriented along the z direction

ze egg

Magnetic field gradientMagnetic field gradient

Magnetic field gradient

Spatially dependentmagnetic field

For a single and constant gradient oriented along the z direction

Notion of effective gradient

Coherenceorder

Phase shift of nuclear spinsPhase shift of nuclear spins• Assume that the magnetic fieldgradient is active during a time

• A nuclear spin acquires a phase shift

)()( 0 zgBz e

Static Field

• Assume that the magnetic fieldgradient is active during a time

Phase shift of nuclear spinsPhase shift of nuclear spins

)()( 0 zgBz e

Gradient

Phase shift of nuclear spinsPhase shift of nuclear spins• Assume that the magnetic fieldgradient is active during a time

The spatial position of the nuclear spins is encoded into a phase shift

Nuclear spin spatial labellingNuclear spin spatial labelling

)()( 0 zgBz e

zgz e)(

Rotating frameRotating frame• In NMR, a common simplification

consists in describing the evolution of the magnetization in a frame rotating at the Larmor frequency 0

• For nuclear spins on resonance, the phase shift reduces to

Spin Echo or Hahn Echo (SE)Spin Echo or Hahn Echo (SE)Without magnetic field gradients

Signal

23coding decoding

Spin Echo or Hahn Echo (SE)Spin Echo or Hahn Echo (SE)With magnetic field gradients

24)( 1z )( 2z

252)( zgp 1)( zgp

p = 1 p = - 1

26 )( 21 zzg

Spin Echo or Hahn Echo (SE)Spin Echo or Hahn Echo (SE)

)( 21 zzg

With magnetic field gradients

Attenuation factor

3exp 2

• Iecho: Intensity at the echo with gradients

• I0: Intensity at the echo without gradients

• D: Self-diffusion coefficient

• : gradient pulse duration

• : Diffusion time

• q: gradient pulse area

Attenuation factor Attenuation factor

29Gradient strength g (G.cm-1)

0 10 20 30

How do we actually obtain How do we actually obtain DD? ? A

3exp 2 gD

Gradient strength g (G.cm-1)

0 10 20 30

How do we actually obtain How do we actually obtain DD? ?

3exp 2 gD

31coding decoding

Stimulated Echo (STE)Stimulated Echo (STE)With magnetic field gradients

BPP-STE-LED sequenceBPP-STE-LED sequence

Stimulated Echo (STE) with Bipolar gradient (BPP) pulses and longitudinal eddy current delay (LED)

The BPP-STE-LED sequenceThe BPP-STE-LED sequence

• Stimulated Echo (STE): – T1 relaxation vs. T2 relaxation– No artefacts due to J modulation

• Bipolar gradient pulses (BPP):– Reduced eddy currents

• Longitudinal Eddy currents Delay (LED):– Less spectral distortions due to eddy currents

Echo Signal

SéquenceSéquenceBPP-STE-LEDBPP-STE-LED

How can we use PGSE data?How can we use PGSE data?

NMR spectrum (frequency scale, ppm)

DA > DC > DB

S I Z ES I Z E

NMR spectrum (ppm scale)

A B C DA > DC > DB

A AB Cppm C

James & McDonald, 1978Stilbs & Moseley, 1978-80

S I Z ES I Z E

Size Resolved SpectrometrySize Resolved Spectrometry

NMR spectrum (ppm scale)

A B C DA > DC > DB

B CCA Appm

Stilbs, 1981

S I Z ES I Z E

ppm A AB C C

• DDiffusion OOrdered NMR SSpectroscopYY– Morris & Johnson, 1992

DOSYDOSY

Antalek, B. Concepts in Magn. Reson 2002, 14, 225-258

DOSYDOSY

Many processings available:- MaxEnt (Delsuc, M. –A.)- DECRA (Antalek, B.)- CORE (Stilbs, P.)- MCR (van Gorkom, L. C. M.)- MULVADO (Huo, R.)- iRRT (Mandelstham, V.)

• DDiffusion OOrdered NMR SSpectroscopYY– Morris & Johnson, 1992– Signal processing

DOSYDOSY

Many processings available:- MaxEnt (Delsuc, M. –A.)- DECRA (Antalek, B.)- CORE (Stilbs, P.)- MCR (van Gorkom, L. C. M.)- MULVADO (Huo, R.)- iRRT (Mandelstham, V.)

• DDiffusion OOrdered NMR SSpectroscopYY– Morris & Johnson, 1992– Signal processing

DOSY mapDOSY map

Adapted from Nilsson et al.

Distortions due to spectral overlapDistortions due to spectral overlap

Adapted from Nilsson et al.

iRRTinverseRegularized ResolventTransform

Mixture of 2 isomers

V. MandelshtamA. J. Shaka

Thureau, P.; Thévand, A.; Ancian, B.; Escavabaja, P.; Armstrong, G. S.; Mandelshtam, V. A., ChemPhysChem 2005, 6, 1

Armstrong, G. S.; Loening, N. M.; Curtis, J. E.; Shaka, A. J.; Mandelshtam, V. A., J. Magn. Reson. 2003, 163, 139

• Part 1: Theory about molecular mobility

– Self-diffusion– Study of self-diffusion by NMR

• Principles of Pulsed Gradient Spin Echo (PGSE)• Diffusion ordered NMR spectroscopy (DOSY)

• Part 2: Selected applications of DOSY

General outlineGeneral outline

Chiral recognitionChiral recognition

Chiral recognition of dipeptides in a biomembrane model

C. Bombelli, S. Borocci, F. Lupi, G. Mancini, L. Mannina, A. L. Segre, S. Viel

J. Am. Chem. Soc. 2004, 126, 13354-13362

IntroductionIntroduction• The organization of biomembranes is based

on molecular recognition phenomena (chiral recognition)

• To investigate the non covalent interactions involved in such systems, models are used

C. Bombelli, S. Borocci, F. Lupi, G. Mancini, L. Mannina, A. L. Segre, S. VielJ. Am. Chem. Soc. 2004, 126, 13354-13362

we used Sodium N-doceanoyl-L-prolinate (SDP)

Here N

C11H23

Introduction (2)Introduction (2)• We studied by NMR the chiral recognition

in SDP micelles of 2 dipeptides

Ditryptophan (1)-

NMR techniques: 1H, PGSE, ROESY+Molecular mechanic calculations

Diphenylalanine (2)

11H experiments: H experiments: LLLL//DDDD couple couple

Ditryptophan (1)+SDP micelles

Diphenylalanine (2)

+SDP micelles

11H experiments: H experiments: LDLD//DLDL couple couple

Ditryptophan (1)

+SDP micelles

Diphenylalanine (2)

+SDP micelles

PGSE experimentsPGSE experiments

• Monitor the D values of the dipeptides by PGSE experiments

• 2-site model: dipeptide in equilibrium between the bound (b) and free (f) phase

SDPD + D

FreeState

BoundState

Monitor the D values of the dipeptides by PGSE experiments

2-site model: dipeptide in equilibrium between the bound (b) and free (f) phase

SDPD + D

fbbbobs DxDxD )1( C. Bombelli, S. Borocci, F. Lupi, G. Mancini, L. Mannina, A. L. Segre, S. VielJ. Am. Chem. Soc. 2004, 126, 13354-13362

• Determine the partition coefficient of the dipeptides in the 2 phases

aqueous

micellar

aqueous

1C. Bombelli, S. Borocci, F. Lupi, G. Mancini, L. Mannina, A. L. Segre, S. VielJ. Am. Chem. Soc. 2004, 126, 13354-13362

PGSE experimentsPGSE experimentsBound molar fractions xb and partition coefficients p

82 ± 120.69 ± 0.03LL-22

82 ± 120.69 ± 0.03DD-22

138 ± 250.79 ± 0.03DL-22

138 ± 250.79 ± 0.03LD-22

931 ± 1000.962 ± 0.004LL-11

860 ± 870.959 ± 0.004DD-11

1900 ± 4070.981 ± 0.004DL-11

1900 ± 4070.981 ± 0.004LD-11

pXbDipeptide:

82 ± 120.69 ± 0.03LL-22

82 ± 120.69 ± 0.03DD-22

138 ± 250.79 ± 0.03DL-22

138 ± 250.79 ± 0.03LD-22

931 ± 1000.962 ± 0.004LL-11

860 ± 870.959 ± 0.004DD-11

1900 ± 4070.981 ± 0.004DL-11

1900 ± 4070.981 ± 0.004LD-11

pXbDipeptide:

82 ± 120.69 ± 0.03LL-22

82 ± 120.69 ± 0.03DD-22

138 ± 250.79 ± 0.03DL-22

138 ± 250.79 ± 0.03LD-22

931 ± 1000.962 ± 0.004LL-11

860 ± 870.959 ± 0.004DD-11

1900 ± 4070.981 ± 0.004DL-11

1900 ± 4070.981 ± 0.004LD-11

pXbDipeptide:

Conformations of Conformations of 11 isomers by NMR and isomers by NMR and Molecular mechanic calculations (1)Molecular mechanic calculations (1)

Buffer

DL-1 1 + BufferLL-1 1 + Buffer

SDP micelles (LL/DD couple)

LL-1 1 + SDPSDP micelles DD-1 1 + SDPSDP micelles

SDP micelles (DL/LD couple)

DL-1 1 + SDPSDP micelles LD-1 1 + SDPSDP micelles

Binding modes of Binding modes of 11 isomers isomers to SDP micellesto SDP micelles

LL/DD couple

Binding modes of Binding modes of 11 isomers isomers to SDP micellesto SDP micelles

LD/DL couple

Chemical exchangeChemical exchange

Determining chemical exchange rates in nucleobases

P. Thureau, B. Ancian, S. Viel, A. ThévandChem. Comm. 2006, 200-202

P. Thureau, B. Ancian, S. Viel, A. ThévandChem. Comm. 2006, 1884-1886

Hydrogen bonding in nucleic acidsHydrogen bonding in nucleic acids

P. Thureau, B. Ancian, S. Viel, A. Thévand Chem. Comm. 2006, 200-202P. Thureau, B. Ancian, S. Viel, A. Thévand Chem. Comm. 2006, 1884-1886

Thymine – Adenine

AdenineUracil –

Effect of chemical exchange in DOSYEffect of chemical exchange in DOSY

Uridine

ModelModel

Simple 2-site exchange

N-H +H2O HOH+N-H

T = 50 ms T = 200 ms T= 900 ms

ModelModel

N-H +H2O HOH+N-H

T = 50 ms T = 200 ms T= 900 ms

ModelModel

N-H +H2O HOH+N-H

T = 50 ms T = 200 ms T= 900 ms

Uracil exchange constants KUracil exchange constants Kaa

N-H +H2O HOH+N-H

H1 ka= 8 s-1

H3 ka= 18 s-1

Thymine exchange constants KThymine exchange constants Kaa

N-H +H2O HOH+N-H

H1 ka= 5 s-1

H3 ka= 7 s-1

Self-aggregationSelf-aggregation

Investigations of complexes in solution

S. Viel, L. Mannina, A. L. SegreTetrahedron Lett. 2002, 43, 2515-2519

C. Sanna, C. La Mesa, L. Mannina, P. Stano, S. Viel, A. L. SegreLangmuir 2006, 22, 6021-6031

stacking interactions are important in organic chemistry and for biological systems

Here we consider 2 types of organic molecules bearing an aromatic ring and characterized by a:

IntroductionIntroduction

- low molecular weight (< 400 Da)

Studied by: - NMR (1H, PGSE, NOESY)- DLS- Physicochemical measurements

- low H2O solubility

S. Viel et al. Tetrahedron Lett. 2002, 43, 2515-2519C. Sanna et al. Langmuir 2006, 22, 6021-6031

Molecules under studyMolecules under studyClass A

Class B

CH3CH3H1DHHOCH31CHHCH31BHHH1AZZYYXXNameName

CH2CH2OCH2CH2CH3CH2CH3PRETCH2OCH2CH3CH3ACET

CH(CH3)CH2OCH3CH3METOYYXXNameName

Monomeric resonances

1H spectra of dilute aqueous solutions of METOMETO, ACETACET and PRETPRET, (Conc < sol)

11H experimentsH experiments

6.97.07.17.27.37.4 ppm 0.91.01.11.2 ppm

1H spectra of dilute aqueous solutions of METOMETO, ACETACET and PRETPRET, (Conc > sol)

11H experimentsH experiments

6.97.07.17.27.37.4 ppm 0.91.01.11.2 ppm

Monomeric resonances

Extra resonances

11H experimentsH experiments1H spectra of dilute aqueous solutions of METOMETO, ACETACET and PRETPRET, (Conc > sol)

6.97.07.17.27.37.4 ppm 0.91.01.11.2 ppm

a b•Well resolved

•Upfield shifted

7 6 5 4 3 2 1 ppm

Aggregate

Monomer

(m s )2 -1

PGSE experiments (DOSY display)PGSE experiments (DOSY display)

PGSE on a dilute aqueous solution of ACETACET

Much lower diffusion coefficient

(nm)(10-11 m2 s-1)(mM)

101.943PRETPRET 151.346METOMETO 111.750ACETACET

Aggregate

0.45043PRETPRET 0.45146METOMETO 0.45350ACETACET

Monomer

RHDNMRConc

Hydrodynamic radiiHydrodynamic radii(Stokes Einstein,Sphere)

NOESY experimentsNOESY experimentsNOESY spectrum of a dilute aqueous solution of ACETACET

400 ms400 ms

Color of cross peaks:

Blue : NegativeGreen/Yellow : Positive

400 ms400 ms

Blue : Negative cross-peakGreen/Yellow : Positive cross-peak

Spin Diffusion

10 ms10 ms

Blue : NegativeGreen/Yellow : Positive

DLS experimentsDLS experiments

Hydrodynamic radiiHydrodynamic radii of the aggregates were also estimated by DLS

(nm)(10-13 m2 s-1)(mM)

3006.52ACETACET 2507.83PRETPRET 7002.813METOMETO

Aggregate

RHDConc

METOMETO

PRETPRET

ACETACET

Physico-chemical propertiesPhysico-chemical propertiesSurface Surface TensionTension

Activity Activity CoeffCoeff

Osmotic Osmotic CoeffCoeff

Rel. viscosityRel. viscosity

Diffusion-Ordered NMR Spectroscopy: a versatile tool for the molecular weight

determination of uncharged polysaccharides

Molecular weightMolecular weight

S. Viel, D. Capitani, L. Mannina, A. L. SegreBiomacromolecules 2003, 4, 1843-1847

90S. Viel, D. Capitani, L. Mannina, A. L. SegreBiomacromolecules 2003, 4, 1843-1847

IntroductionIntroduction•Polysaccharides constitute a major class of biomacromolecules and play key roles in biological recognition processes.

•Their structural elucidation relies mainly on NMR, but a complete characterization may also require the molecular weight (MW).

•Available techniques: Photonic Correlation Spectroscopy, Gel Permeation Chromatography

Drawbacks: sample manipulation

Diffusion and MassDiffusion and Mass•Strictly, diffusion relates to molecular size. A calibration is hence required to establish the relationship between diffusion coefficient and molecular weight

Pullulan (linear polysaccharide)

6 fractions (kDa): 5.8; 12; 28.3; 100; 180 and 853Studied by PGSE experiments

Diffusion and MassDiffusion and Mass

853 kDa5.8 kDa 100 kDa

100 1000 10000 100000 10000001E-11

Pullulan

S. Viel, D. Capitani, L. Mannina, A. L. SegreBiomacromolecules 2003, 4, 1843-1847

Determination of Molecular Weight:Determination of Molecular Weight:Pullulan as a Model SamplePullulan as a Model Sample

MW(Da)

D(m2/s)

Determination of Molecular Weight:Determination of Molecular Weight:Calibration curveCalibration curve

100 1000 10000 100000 10000001E-11

Pullulan Calibration Curve

D(m2/s)

MW(Da)

Determination of Molecular Weight:Determination of Molecular Weight:Check with another polysaccharideCheck with another polysaccharide

D(m2/s)

MW(Da)100 1000 10000 100000 1000000

Calibration Curve Dextran

Determination of Molecular Weight:Determination of Molecular Weight:Check with oligosaccharidesCheck with oligosaccharides

D(m2/s)

MW(Da)100 1000 10000 100000 1000000

Calibration Curve Dextran Cyclodextrins - Oligosaccharide

Determination of Molecular Weight:Determination of Molecular Weight:Check with saccharidesCheck with saccharides

D(m2/s)

MW(Da)100 1000 10000 100000 1000000

Calibration Curve Dextran Cyclodextrins - Oligosaccharide Saccharides

Use of Pulsed Field Gradient Spin-Echo NMR as a tool in MALDI method

development for polymer Mw determination

Molecular WeightMolecular Weight

M. Mazarin, S. Viel, B. Allard-Breton, A. Thévand, L. CharlesAnal. Chem. 2006, 78, 2758-2764

PolymersPolymers

M. Mazarin, S. Viel, B. Allard-Breton, A. Thévand, L. CharlesAnal. Chem. 2006, 78, 2758-2764

pMAMpMAM

Concentration (mg.mL-1)

0.0 1.0 2.0 3.0 4.0

2.0e-10

4.0e-10

6.0e-10

8.0e-10

1.0e-9

1.2e-9

1.4e-9

Mw 309 (D0 = 1.172e-9)

Mw 972 (D0 = 6.596e-10)

Mw 3460 (D0 = 3.405e-10)

Mw 9830 (D0 = 1.973e-10)

Mw 23800 (D0 = 1.189e-10)

Mw 74500 (D0 = 5.903e-11)

D=f[PS] D0PS=f(Mw)

Molecular weight Mw (Da)

10 100 1000 10000 100000 1000000

(m2 .s

0.54122.721448e-8

Polymers Polymers PSPS

D = k Mw -a

PS : Comparison Mw : SEC, NMR and MS

12.012.1(Fluka)

83416 2038353974500PS 70000

-3.8-3.8(Fluka)

22890 492290723800PS 20000

-4.6-8.6(Fluka)

9375 1089869830PS 10000

0.3-5.2(Fluka)

3470 432783460PS 3000

-5.6-0.6(Fluka)

918 6966972PS 1000

40.5-8.1(Sigma-Aldrich)

434 10334309PS 400

MALDI-TOF-MSNMRSEC (provider)PS standards

Analysis of mixtures (part I)Analysis of mixtures (part I)

Improved 3D DOSY-TOCSY experiment for mixture analysis

S. Viel, S. CaldarelliChem. Comm. 2008, in press

103S. Viel, S. Caldarelli

Chem. Comm. 2008, in press

•Overlapping signals severely complicate DOSY analysis

•A typical solution is the addition of another frequency dimension to spread the signals out

Drawback: time consuming experiments due to the requirement of sampling the indirect frequency dimension

Speeding up 3D NMR Speeding up 3D NMR experimentsexperiments

•Various methodologies have been proposed to speed up 3D NMR experiments (FDM)

S. Viel, S. Caldarelli

•Various methodologies have been proposed to speed up 3D NMR experiments (FDM)

•One possibility is Hadamard (there are other ones

………...….….3D iRRT would be great!)

•Various methodologies have been proposed to speed up 3D NMR experiments

•One possibility is Hadamard (there are other ones

………...….….3D iRRT would be great!)

•In Hadamard NMR spectroscopy, the evolution time in the indirect dimension of the 2D block is replaced by phase-encoded multisite selective excitation

Hadamard encodingHadamard encoding

Hadamard family matrices HMatrix dimension N:N = 2k (k = 1, 2, 3…)

+––+––++–+–+++++

Pulse 1

Pulse 2

Pulse 3

Pulse 4

A B C D

– HHHH

M chemical sites NM

–+++

+––+––++–+–+++++

Pulse 1

Pulse 2

Pulse 3

Pulse 4

A B C D

M chemical sites NM – HHHH

–+++

+––+––++–+–+++++

Pulse 1

Pulse 2

Pulse 3

Pulse 4

A B C D

M chemical sites NM – HHHH

–+++

+––+––++–+–+++++

Pulse 1

Pulse 2

Pulse 3

Pulse 4

A B C D

Signal B = + 1 – 2 + 3 – 4M chemical sites NM – HHHH

–+++

Proposed pulse sequenceProposed pulse sequence

Thrippleton, M. J.; Keeler, J., Angew. Chem. Int. Ed. 2003, 42, 3938-3941.

Cano, K. E.; Thrippleton, M.; Keeler, J.; Shaka, A. J., J. Magn. Reson. 2004, 167, 291-297.ZQC filters

Proof of principle (1)Proof of principle (1)

TOCSY spectrum of a mixture of:

- Methanol (M)- Ethanol (E)- Propanol (P)- Valine (V)

Proof of principle (2)Proof of principle (2)

Effect of signal overlappingEffect of signal overlapping

Propanol

2-Butanol

Effect of signal overlapping (2)Effect of signal overlapping (2)

Time saving factor: 64

Analysis of mixtures (part II)Analysis of mixtures (part II)

Enhanced diffusion-edited NMR spectroscopy of mixtures using

chromatographic stationary phases

S. Viel, F. Ziarelli, S. CaldarelliProc. Natl. Acad. Sci. U. S. A. 2003, 100, 9696-9698

Can we selectively slow down the diffusion of some components of the mixture?

S. Viel, F. Ziarelli, S. Caldarelli

Proceedings of the National Academy of Sciences of the United States of America 2003, 100, 9696-9698

•PGSE experiments allow compounds to be discriminated according to differences in their effective size (mixture analysis)

•Corollary: similar sized compounds CANNOT be resolved by PGSE

Chromatographic phases

118S. Viel, F. Ziarelli, S. Caldarelli

PrinciplePrinciple

•A chromatographic phase interacts selectively with some of the mixture components (for instance: polarity/apolarity)

•Discrimination is achieved according to apparent diffusion rates(instead of free self-diffusion coefficients)

Problem: spectral resolution!Problem: spectral resolution!1H of Sol. + Stationary phase

Conventional NMRHHigh RResolutionMMagic AAngle SSpinning: solid state technique

Problem: spectral resolution!Problem: spectral resolution!1H of Sol. + Stationary phase

Conventional NMRHHigh RResolutionMMagic AAngle SSpinning: solid state technique

HRMAS NMR

HRMASHRMAS

HRMAS rotorHRMASprobe

Example 1Example 1

Mixture 1:Mixture 1:- Dichlorophenol- Ethanol- Heptane

Example 1Example 1

Mixture 1:Mixture 1:- Dichlorophenol- Ethanol- Heptane

Example 2Example 2

Mixture 2:Mixture 2:- Naphtalene- Dec-1-ene - Ethanol

Example 2Example 2

Mixture 2:Mixture 2:- Naphtalene- Dec-1-ene - Ethanol

Research directionsResearch directions

• Improve resolution of complex mixtures

• Characterize new chromatographic phases

• Investigate chromatographic phenomenon

• Discriminate stereoisomers

PFG MAS diffusion PFG MAS diffusion measurementsmeasurements

Pulsed field gradient magic angle spinning NMR self-diffusion

measurements in liquids

S. Viel, F. Ziarelli, G. Pagès, C. Carrara, S. CaldarelliJ. Magn. Reson. 2008, 190, 113-123

Gradients and MAS probesGradients and MAS probes

S. Viel, F. Ziarelli, G. Pagès, C. Carrara, S. Caldarelli