Improved Analysis of Fatty Acids by Capillary GC columns based on Ionic Liquids F. Michel, L.M. Sidisky, M.D. Buchanan, G.A. Baney, Y. Ni,J.L.

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1 Improved Analysis of Fatty Acids by Capillary GC columns based on Ionic Liquids F. Michel, L.M. Sidisky, M.D. Buchanan, G.A. Baney, Y. Ni,J.L. Desorcie, and K.K. Stenerson

O Introduction HO CH 3 CH 3 HO O Estimation: replacing of transfats by plant oils may prevent up to 100.

2 O Introduction HO CH 3 CH 3 HO O Estimation: replacing of transfats by plant oils may prevent up to premature fatal incidents per year ( eviews/transfats.html) O CH 3 2 HO

3 Introduction Fatty acids are typically separated by GC as their methyl esters (FAME) Capillary column choice for FAME analysis will depend upon the information required from the analysis. Non-polar columns are routinely used to provide results on the amount of saturated versus unsaturated fatty acids. Polyethylene glycol based columns are used to provide carbon chain length & degree of saturation resolution. The analysis of cis and trans FAMEs, along with resolving their positional isomers, requires the use of highly polar biscyanopropyl polysiloxane columns [1]. [1] AOCS Method Ce 1h-05, Determination of cis-, trans-, Saturated, Monounsaturated and Polyunsaturated Fatty Acids in Vegetable or Non-ruminant Animal Oils and Fats by Capillary GLC AOCS Official Methods (2005) American Oil Chemists Society. 3

4 Fatty Acid / FAME Chemistry FAME Structures Why use derivatization? The active carboxyl group has a much stronger interaction with the stationary phase than the remainder of the analyte Neutralizing the carboxyl group interactions allows slight differences in interaction strengths resulting from saturation level and double bond orientation to be observed Derivatization via an esterification reaction Short chain fatty acids are often analyzed in their free form using GC. Long chain fatty acids are often analyzed as FAMEs using GC. 4 sigma-aldrich.com/fame

5 Derivatization of Fatty Acids 5

6 Click on Technical Literature 6

7 Technical Literature on Derivatization 7

8 The limit of classic method for FAME analysis Extracted fat from margarine Overlap of trans/cis monounsaturated octadecenoic fatty acids on the GC chromatogram of a biscyanopropyl siloxane phase 16:0 18:0 18:1 18:2 18: t 9t 10t 11t 12t 13t 6c 7c 9c Peaks from 18:1 trans and cis isomers overlap 10c 11c 12c 13c

9 SPE approach to overcome co-elution of cis- and trans-fames Use of silver-ion loaded SPE material for separation of cis- /trans-fames W. Christie: Ag-ion SPE for separation of FAMEs according to their degree of saturation in 1989 Japanese research group (Food Analysis): Custom made Agion SPE cartridge for separation of cis-/trans isomer up to trienes in 2005

10 How does it work? Silver ions immobilized onto SCX SPE phase The FAMEs sample extract is passed through the cartridge Ag ions interact with the double-bonds of the FAMEs The more double bonds, the greater the retention Cis-isomers retain stronger than trans-isomers

11 How Is It Used? Fatty acids (FA) extracted from food sample FA converted to FAMEs using BF3 FAMEs are extracted into hexane Hexane sample applied to Discovery Ag-ION SPE cartridge FAMEs separated using different mixtures of hexane:acetone to extract from cartridge Fractions analyzed by GC-MS (SP-2560 capillary column).

12 Discovery Ag-ION Protocol

13 Fractionation of the standard FAME mixture Standard sample, total FAMEs at 1 mg/ml Standard Mixture 14:0 16:0 18:0 18:1 18:2 18: SPE fraction1 18:1 t Hexane: Acetone 96: SPE fraction 2 18:1 c Hexane: Acetone 90: SPE fraction 3 Acetone SPE fraction 4 Acetonitrile

14 GC Results of Cis/Trans Fractionation of Potato Chips column: SP-2560, 75 m x 0.18 mm I.D., 0.14 µm (23348-U) oven: 180 C, isothermal inj.: 220 C det.: FID, 220 C carrier gas: hydrogen, 40 cm/sec. at 180 C injection: 0.5 µl, 100:1 split liner: 4 mm I.D., split, cup design

15 Discovery Ag-Ion SPE Technical Report T (IRV) U 750 mg/6 ml SPE Tube U 750 mg/1 ml Rezorian

16 Improvements in the GC Analysis of FAMEs 17

17 Introduction Structure of Polysiloxane and PEG Polymer Phase R 1 R 3 HO Si O Si O H HO CH 2 CH 2 O CH 2 CH 2 O CH 2 CH 2 OH R 2 R 4 x y n Drawbacks Active hydroxyl (-OH) groups at the polymer termini allow a back-biting reaction Resulting in phase degradation Contributing to column bleed Chemistry modifications are limited to pendent group changes PEG/Wax: Limited to 280 C maximum temperature R = methyl, phenyl, fluoropropyl, and/or cyanopropyl (least polar to most polar). x,y = percentage in the overall polymer composition. 18

18 Definition, Early Literature, and Use of Ionic Liquids Ionic liquids are a class of solvents with low melting points that consist of organic cations associated with (inorganic or organic) anions Ethyl ammonium nitrate (C 2 H 5 NH 3+ )(NO 3- ), which has a melting point of 12 o C, was described in 1914 P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 1800 (1914) Today, they are used as solvents, electrically conducting fluids, and sealants 19

19 Ionic Liquids Water Ionic Liquid CHCl 3 Source: Prof. Jared Anderson, University of Toledo, USA 20

20 Ionic Liquids in GC Several properties make ionic liquids desirable as GC stationary phases Very low volatility should result in columns with lower bleed and longer life Remain in the liquid state over a wide temperature range should result in columns with extended temperature ranges No active hydroxyl (-OH) groups at their termini should result in columns resistant to damage from moisture/oxygen 21

21 Ionic Liquids in GC Several properties make ionic liquids desirable as GC stationary phases Are inherently highly polar should result in columns with higher polarity that have lower elution temperatures plus an increased selectivity for polarizable analytes Have the broadest range of physical-chemical solvation interactions of any solvent should result in columns with unique selectivity High viscosity should be easy to coat columns 22

22 Example Structure of an Ionic Liquid Phase Phase used to make the SLB-IL100 1,9-di(3-vinylimidazolium) nonane bis(trifluoromethyl) sulfonyl imide Numerous combinations of cations, anions and linkers are possible allowing for tailored selectivity or application Dicationic (shown) or polycationic Cations (imidazolium, phosphonium, pyrrolidinium, ), anions (NTf2 -, triflat, tetrafluoroborate, hexafluorophosphate, ), and linkages (alkanes, polyethylenglycols, different lengths, ) can be changed Pendant groups can be added to cations and/or linkages 24

23 GC Column Polarity Scale Visual Representation Non-Ionic Liquid Phases Non- Polar Intermediate Polar Polar Highly Polar Extremely Polar Ionic Liquid Phases Above the scale: positions/maximum temperatures of non-ionic liquid columns. Below the scale: positions/maximum temperatures of Supelco ionic liquid columns. 26

24 Selectivity: Test Mix Peak IDs and Conditions Peak IDs (listed in boiling point order) Toluene Ethylbenzene p-xylene Isopropylbenzene (Cumene) Cyclohexanone 1,2,4-Trimethylbenzene 1,2,4,5-Tetramethylbenzene n-tridecane (C13) Conditions columns: 30 m x 0.25 mm I.D., 0.20 µm oven: 110 C inj.: 250 C det.: FID, 250 C carrier gas: helium, 26 cm/sec injection: 1.0 µl, 100:1 split sample: each analyte at various concentrations in isooctane 27

25 Selectivity: Test Mix on Ionic Liquid Columns 30 m Columns, 110 C Isothermal 8 SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL

26 Rapeseed Oil FAME Peak IDs and Conditions Peak IDs and composition Myristic 1.0% Palmitic 4.0% Stearic 3.0% Oleic 60.0% Linoleic 12.0% Linolenic 5.0% Arachidic 3.0% cis-11-eicosenoic 1.0% Behenic 3.0% Erucic 5.0% Lignoceric 3.0% Conditions columns: 30 m x 0.25 mm x 0.20 µm oven: 180 C isothermal inj.: 250 C det.: FID, 250 C carrier gas: helium, 25 cm/sec injection: 1.0 µl, split 100:1 liner: 4 mm I.D., split type, cup design sample: Rapeseed oil FAME mix (O7756-1AMP) diluted to 10 mg/ml in methylene chloride 29

27 SLB-IL59 Rapeseed Oil FAMEs on Ionic Liquid Columns 30 m Columns, 180 C Isothermal SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL : C18:3 7: C20:0 8: C20:

28 Partially Hydrogenated Vegetable Oil (PHVO) FAMEs SP-2560 SLB-IL111 31

29 Partially Hydrogenated Vegetable Oil (PHVO) FAMEs When comparing FAME isomers with the same degree of unsaturation, the SLB-IL111 provides increased retention of cis isomers relative to trans isomers with the double bond at the same location The SLB-IL111 was able to provide resolution of C18:1 9c from C18:1 15t, a separation not possible with the SP The SLB-IL111 offered improved resolution of some isomers that cannot be completely resolved with the SP-2560 either C18:1 10t from C18:1 11t The pair C18:1 13t/C18:1 14t from other isomers 32

30 CLA FAMEs in Ruminant Fats The SLB-IL111 is able to resolve C18:2 9c,11t from C18:2 7t,9c the two most abundant conjugated linoleic acid (CLA) isomers found in ruminant fats [5] No other column can resolve these SLB-IL111 as complementary column (to biscyanopropyl polysiloxane) for complete analysis of cis- and trans-fat [5] P. Delmonte, A.-R.F. Kia, J.K.G. Kramer, M.M. Mossoba, L. Sidisky, J.I. Rader, J. Chrom. A, 1218 (2011)

31 To Learn More Visit the Ionic Liquid GC column landing page (sigmaaldrich.com/il-gc) at the Sigma-Aldrich web site Download or request Supelco Ionic Liquid GC Columns: Applications Download or request Supelco Ionic Liquid GC Columns: Bibliography 34 sigma-aldrich.com/il-gc

32 Summary Ag-Ion SPE provides a separation of cis and trans FAMEs Allow for a complete separation of the critical mono-unsaturated C18 FAMEs Correct calculation of amount of cis/trans fatty acids Alternative approach to using SLB-IL111 and biscyanopropyl polysiloxane phases (e.g. SP-2560) as complementary column SLB-IL111 as complementary column to biscyanopropyl polysiloxane phases allows the complete analysis of cis and trans fatty acids Separation of several isomers that could not be resolved before Further publications on FAME analysis on Ionic Liquid GC [6] [6] F. Destaillats, M. Guitard, C. Cruz-Hernandez, J. Chrom. A, 1218 (2011)

$fractionation of FAMEs Analysis of FAMEs by boiling point elution Analysis of FAMEs by degree of unsaturation Analysis of omega 3 and omega 6 FAMEs Analysis of cis/trans FAME isomers Also includes: A$

33 Fatty Acid/FAME Application Guide (T408126, KUK) 24-page brochure Includes columns, standards, and other products for the: Analysis of free fatty acids Derivatization of fatty acids to FAMEs SPE fractionation of FAMEs Analysis of FAMEs by boiling point elution Analysis of FAMEs by degree of unsaturation Analysis of omega 3 and omega 6 FAMEs Analysis of cis/trans FAME isomers Also includes: A list of non-supelco references A list of our product literature 36

34 Dziękuję za uwagę! Prof. Dan Armstrong, University of Texas at Arlington Prof. Luigi Mondello, University of Messina, Italy sigma-aldrich.com/fastgc Dr. Pierluigi Delmonte, US FDA 37

Evaluation of a New Ionic Liquid Stationary Phase with PEG Like Selectivity

Evaluation of a New Ionic Liquid Stationary Phase with PEG Like Selectivity L.M.Sidisky, G. A. Baney, J.L. Desorcie, D.L. Shollenberger, G. Serrano, and K.K. Stenerson Supelco, Div. of Sigma-Aldrich Bellefonte,