New Developments in Ionic Liquid GC Stationary Phases

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K. Stenerson May 1, 2013 ISCC, Palm Springs, CA sigma-aldrich.

1 New Developments in Ionic Liquid GC Stationary Phases L.M.Sidisky, G. A. Baney, J.L. Desorcie, D.L. Shollenberger, G. Serrano, K.K. Stenerson May 1, 2013 ISCC, Palm Springs, CA sigma-aldrich.com/analytical 1 Overview of Presentation Overview of Ionic Liquids Selectivity Evaluations Selectivity Ranking/ Assignment SLB-IL111 SLB-IL0 Conclusions 2 1

2 Ionic Liquids: Definition and Uses 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 (EtNH + 3)(NO - 3), which has a melting point of 12 C, was described in 1914 P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 100 (1914) Today, they are used as solvents, electrically conducting fluids, and sealants 3 sigma-aldrich.com/il-gc Ionic Liquids: Example Structure SLB-IL100 1,9-di(3-vinylimidazolium) nonane bis(trifluoromethyl) sulfonyl imidate Benefits Greater stability compared to polysiloxane polymers and polyethylene glycols Lower column bleed, longer life, and higher thermal limits More resistant to damage from moisture/oxygen Numerous combinations of cations and anions are possible allowing for tailored selectivity, application, or function Dicationic (shown) or polycationic Cations, linkages, and/or anions can be changed Pendant groups can be added to cations and/or linkages 4 sigma-aldrich.com/il-gc 2

in methylene chloride 5/20/2013 Selectivity Evaluations 5 How do the selectivities of the different ionic liquid phases compare to each other? Compare elution using probes in: 1.

3 in methylene chloride 5/20/2013 Selectivity Evaluations 5 How do the selectivities of the different ionic liquid phases compare to each other? Compare elution using probes in: 1. Test mix containing aliphatic and aromatic hydrocarbons 2. Rapeseed fatty acid methyl esters (FAMEs) 1. IL test mix 2. Rapeseed FAMEs Peak IDs (listed in boiling point order) 1. Toluene, BP=110. º C 2. Ethylbenzene 3. p-xylene 4. Isopropylbenzene (Cumene) 5. Cyclohexanone, BP=155 º C. 1,2,4-Trimethylbenzene. 1,2,4,5-Tetramethylbenzene. n-tridecane (C13), BP=234 º C Conditions columns: 30 m x 0.25 mm I.D., 0.20 µm oven: 110 ºC inj.: 250 ºC det.: FID, 250 ºC carrier gas: helium, 2 cm/sec injection: 1.0 µl, 100:1 split Peak IDs and composition Rapeseed contains a 1. Myristic 1.0% series of saturated and 2. Palmitic 4.0% unsaturated fatty acids 3. Stearic 3.0% ranging from C14 4. Oleic 0.0% through C24 5. Linoleic 12.0%. Linolenic 5.0%. Arachidic 3.0%. cis-11-eicosenoic 1.0% 9. Behenic 3.0% 10. Erucic 5.0% 11. Lignoceric 3.0% Conditions columns: 30 m x 0.25 mm I.D., 0.20 µm oven: 10 ºC isothermal inj.: 250 ºC det.: FID, 250 ºC carrier gas: helium, 25 cm/sec constant sample: each analyte at various concentrations in isooctane injection: 1.0 µl, split 100:1 liner: 4 mm I.D., split type, cup design sample: Rapeseed oil FAME mix (O5-1AMP) diluted to 10 mg/ml 3

4 /20/2013 Test Mix on Ionic Liquid Columns 30 m Columns, 110 ºC Isothermal T Decreasing retention of C13 as polarity increases C13 Cy: BP=155 ºC C13: BP=234 ºC SLB-IL59 Due to C=O, always exhibits strongest retention O Cy T C13 SLB-IL1 Cy T C13 SLB-IL Cy Increasing polarity T C13 SLB-IL2 Cy T C13 SLB-IL100 Cy C13 T SLB-IL111 Cy Fatty Acid Methyl Ester (FAME) Analysis Separation Chain length (boiling point) Chain length/degree of unsaturation Traditional Column Methylsilicone (X-1) PEG-phases (X-wax) Recommended Ionic Liquid Column None SLB-IL0 Cis/trans groups Cyanopropylsilicones SLB-IL100 SLB-IL111 Advantage of Ionic Liquid 1.Higher max temp. 2.Better phase stability 3.Different selectivity 4.Shorter elution time Cis/trans groups & geometric positional isomers Highest polarity cyanopropylsilicones SLB-IL111 Examples of cyanopropylsilicone columns are: SP-2330, SP-2331, SP-230, SP-250 (highest polarity) 4

5 /20/2013 Rapeseed Oil FAMEs on Ionic Liquid Columns 30 m Columns, 110 ºC Isothermal SLB-IL59 Relative retention of C1:3 increases with polarity while C20:0 decreases SLB-IL1 SLB-IL Increasing polarity SLB-IL2 SLB-IL100 SLB-IL111 =C1:3 =C20:0 =C20:1 3 double bonds 9 0 double bonds 1 double bond FAME Equivalent Chain Length (ECL) Values FAME ECL 10 ºC C1:1n9c C1:2n C1:3n C20:1n9 C22:1n9 SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL SLB-IL SUPELCOWAX 10* SP -230* sigma-aldrich.com/il-gc 5

6 GC Column Polarity Scale and Naming System 11 sigma-aldrich.com/il-gc Experimentally Determined Polarity Numbers P (Polarity) = sum of the first 5 McReynolds Constants. P.N. (Polarity Number) = Polarity (P) normalized to SLB-IL100 (set at P=100). 12 sigma-aldrich.com/il-gc

7 Visual Representation 13 sigma-aldrich.com/il-gc SLB-IL111 14

8 SLB-IL111 Phase Structure 1,5-Di(2,3-dimethylimidazolium)pentane bis(trifluoromethylsulfonyl)imide 15 sigma-aldrich.com/il-gc What about polar columns for benzene in gasoline? 50-20º C (50-140º C TCEP) SUPELCOWAX 10, 30 m Last to elute=1mn (13.3 min.) Benzene is resolved from ethanol on all columns TCEP and SLB-IL111 provide best resolution of benzene from aliphatics SUPELCOWAX 10: benzene between C9 & C10 TCEP and SLB-IL111: benzene after C11 TCEP has a low max. temp., so a long run time is required to elute the last components in the gasoline SLB-IL111 has the shortest elution time overall Last to elute=1mn (39.4 min.) SLB-IL111, 30 m Last to elute=1mn (11. min.) TCEP, 0m 1

Gasoline containing other oxygenates C5-C11 HCs 1 4 No interference in detection of benzene + unknown 1. Methyl tert-butyl ether (MTBE). o-xylene 2. tert-amyl ether (TAME) 9. 1,2,4-Trimethylbenzene 3.

1-Methyl naphthalene 9 spiked with 10% MTBE, 1% TAME 2 3 5 10 11 Eluting heavier compounds in reasonable time 12 13 14 2 4 10 12 Conditions column: SLB IL-111, 30 m x 0.25 mm I.D. x.20 µm, oven: 50 ºC (3 min.

9 Gasoline containing other oxygenates C5-C11 HCs 1 4 No interference in detection of benzene + unknown 1. Methyl tert-butyl ether (MTBE). o-xylene 2. tert-amyl ether (TAME) 9. 1,2,4-Trimethylbenzene 3. Benzene 10. 1,2,3-Trimethylbenzene 4. Toluene 11. 1,2,4,5-Tetramethylbenzene 5. Ethyl benzene 12. Naphthalene. p-xylene Methyl naphthalene. m-xylene Methyl naphthalene 9 spiked with 10% MTBE, 1% TAME Eluting heavier compounds in reasonable time Conditions column: SLB IL-111, 30 m x 0.25 mm I.D. x.20 µm, oven: 50 ºC (3 min.), 15 ºC/min. to 25 ºC (5 min.) inj. temp.: 250 ºC carrier gas: helium, 30 cm/sec, constant detector: FID, 25 ºC injection: µl, 200:1 split liner: 4 mm I.D. FocusLiner inlet liner with taper sample: Premium Unleaded Gasoline, prepared as indicated 1 Analysis of Biodiesel Mixtures Biodiesel is a mixture of fatty acid methyl esters (FAMEs) The properties of biodiesel are determined by the FAME composition FAME profile is a test to determine biodiesel quality PEG-based phases normally used for testing Biodiesel can be used in a pure mixture or mixed with petro-based diesel 100% biodiesel is called B100 Mixtures are denoted by the percent biodiesel they contain. For example, 20% biodiesel is B20. FAME profile testing on mixed biodiesel samples can be difficult due to interference from petroleum-based portion SLB-IL111 Higher polarity than PEG-based phases Better separation between FAMEs and petroleum constituents in mixed biodiesel 1 9

10 Analysis of B20 Biodiesel - SLB-IL111 vs. Omegawax C22 Omegawax 250 C1:0 elutes after C22 HC SLB-IL111 Weaker retention of HCs C25 C1:0 elutes after C25 hydrocarbon Higher polarity SLB-IL111 shows weaker retention of hydrocarbons relative to FAMEs than the Omegawax Fame Elution Order- SLB-IL111 compared to highly polar SP Resolution of all 3 FAMEs on both columns - different selectivity SLB-IL111 Shorter elution time Analysis conditions optimized on each column SP For analysis conditions and peak IDs, see appendix

Cis/Trans FAME separations C1:1 cis/trans isomers of specific interest Need high polarity phases to separate cis and trans geometric positional isomers Normally use

and complimentary selectivity to cyanopropylsilicone phases C1:1 isomers on SLB-IL111 C1:0 1 20 22 C1:1 isomers C1:0 C1:3 Column: SLB-IL111, 30 m x 0.

: FID, 250 ºC Carrier: helium, 20 cm/sec, constant Injection: 1 µl, split 100:1 Liner: 4 mm ID, focus liner w/taper Sample: cis/trans isomer mix; 2.

11 Cis/Trans FAME separations C1:1 cis/trans isomers of specific interest Need high polarity phases to separate cis and trans geometric positional isomers Normally use cyanopropylsilicone phases 100 m SP-250 is a mainstay column for this application Ionic liquid columns SLB-IL100 and SLB-IL111 provide resolution of cis/trans isomers and complimentary selectivity to cyanopropylsilicone phases C1:1 isomers on SLB-IL111 C1: C1:1 isomers C1:0 C1:3 Column: SLB-IL111, 30 m x 0.25 mm I.D. x 0.20 µm Oven: 135 ºC, (22 min.), 10 ºC/min. to 10 ºC C1:2 Inj.: 250 ºC Det.: FID, 250 ºC Carrier: helium, 20 cm/sec, constant Injection: 1 µl, split 100:1 Liner: 4 mm ID, focus liner w/taper Sample: cis/trans isomer mix; 2.5 mg/ml in methylene chloride C20:0 C20: C1 FAME Isomers: SLB-IL100 vs. SP m column Better resolution Better resolution of C1:1 isomers on 100 m SP-250 Better resolution of C1:3 isomers on 0 m SLB-IL100 Shorter elution time on SLB-IL100 0 m column Better resolution 22 11

12 C1:1 cis/trans FAME Isomers in Partially Hydrogenated Vegetable Oil (PHVO) SLB-IL111 vs. SP-250: 100 m columns SLB-IL111: Increased retention of cis relative to trans complimentary selectivity 23 sigma-aldrich.com/il-gc SLB-IL

13 Why SLB-IL0? Improved inertness over SLB-IL59 Complimentary selectivity to PEG phases Higher maximum temperature than PEG phases Lower bleed than PEG phases 25 Improved Inertness C1-C12 n-alcohols C isothermal Severe tailing SLB-IL59 C-OL C9-C12 alcohols adsorbed C-OL C9-OL C10-OL C11-OL SLB-IL0 C12-OL

14 Complimentary Selectivity to Wax SLB-IL Wax Octanone 2. n-c15 3. n-octanol 4. n-c1 5. n-c1. n-c1. 2,-Dimethylphenol. 2,-Dimethylaniline 9. n-c Higher Max Temp and Lower Bleed than Wax AU SLB-IL0, T f = 300 C pA FID bleed at published counts Wax #1, T f = 20 C temp. program max pA AU Wax #2, T f = 300 C 129pA

15 Chlorinated solvents on the SLB-IL0 & Wax SLB-IL0 All resolved yet faster elution , 2 Wax ,1-Dichloroethylene 2. trans-1,2-dichloroethylene 3. Methylene chloride 4. 1,1-Dichloroethane 5. Carbon tetrachloride. 1,1,1-Trichloroethane. Chloroform. Trichloroethylene 9. 1,2-Dichloroethane 10. Tetrachloroethene 11. 1,1,1,2-Tetrachloroethane 12. 1,1,2,2-Tetrachloroethane SLB-IL0: 30 m x 0.25 mm I.D. x 0.20 µm Wax: 30 m x 0.25 mm I.D. x 0.25 µm Oven: 40 C (4 min.), C/min. to 200 C Helium, 30 cm/sec, set at 120 C Cis/ trans FAMES on SLB-IL0 vs. PEG Type Phase C1:1n9 cis / trans 10 C trans cis SLB-IL0 PEG C1:2n cis & trans FAME Isomers- 10 C C1:2n tt C1:2n tt C1:2n cc C1:2n cc

16 Fame Elution order- SLB-IL 0 compared to Wax 1: C1:1n9c 1: C1:1n9t 19: C1:2nc 20: C1:2nt SUPELCOWAX 10 2: C20:3n 2: C20:3n3 35: C22:5n3 3: C24:0 3: C22:n3 SLB-IL0 Notable elution changes from wax column: 1. C1:1n9t elutes before C1:1n9c 2. C1:2nt elutes before C1:2nc 3. C20:3n3 elutes before C20:3n 4. C22:n3 elutes before C22:5n3 and C24:0 C24:0 31 PUFA 3 Standard C14:0 C1:0 C1:1n C1:1n9 C20:5n3, C20:4n3? C22:n3 C1:2n4 C1:3n4 C1:0 C1:1n C1:2n C1:3n3 C1:3n4 C1:4n3 C20:4n C20:1n9 C20:3n3 C22:5n3 SLB-IL0 C14: C1:1n C20:5n3 C1:0 C22:n3 C1:1n9 C1:1n C1:3n4 C1:4n3 C20:4n Omegawax 250 C1:2n4 C1:3n4 C1:0 C1:2n C1:3n3 C20:1n9 C20:4n3 C20:3n3 C22:5n Same analysis conditions as 3-component mix 1

17 Extract of Farm-Raised Atlantic Salmon C1:0 C1:1n9 C14:0 C1:1n C1:2n C1:3n SLB-IL0 C1:3n4 C1:3n4 C1:0 C1:1n C1:2n4 C1:3n3 C1:4n3 C20:5n3 C20:3n3 C20:4n3? C20:1n9 C20:4n C22:1n9 C22:n3 C22:5n BHT C1:0 C1:1n9 C1:2n C14:0 C1:1n C1:1n C1:3n C1:3n3 C1:4n3 C1:2n4 C1:0 C1:3n4 C1:3n4 C20:1n9 C20:5n3 C20:4n C20:3n3 C20:4n3 Omegawax 250 C22:n3 C22:5n Samples prepared using AOCS Official Method Ce 1k-09; BHT added as an antioxidant Window Diagram Studies ECL 10 C C1:1n9 C1:2n C1:3n C20:1n9 C22:1n9 k C24:0 SLB-IL SLB-IL

18 Window Diagram Experiments 200 C - ECL Values ECL Values C1:1n9c C1:2nc C1:3n C20:1n9 C22:1n % Imidazolium/ Phosphonium PAHs on SLB-IL Resolution of all isomer sets These three cannot be resolved on a nonpolar column Improved resolution compared to a nonpolar column column: SLB-IL59, 20 m x 0.1 mm I.D., 0.14 µm oven: 5 ºC (0.5 min), 25 ºC/min to 300 ºC (20 min) inj. temp.: 25 ºC carrier gas: helium, 50 psi constant pressure detector: MSD, full scan, m/z= MS interface: 300 ºC Injection: 1 µl, splitless (1 min) liner: 4 mm I.D. FocusLiner w/taper sample: PAHs, 10 ug/ml in methylene chloride Naphthalene 2. Acenaphthene 3. Acenaphthylene 4. Fluorene 5. Phenanthrene. Anthracene. Fluoranthene. Pyrene 9. Benzo[a]anthracene 10. Chrysene 11. Benzo[b]fluoranthene 12. Benzo[k]fluoranthene 13. Benzo[j] fluoranthene 14. Benzo[a]pyrene 15. Indeno[1,2,3-cd]pyrene 1. Dibenzo[a,h]anthracene 1. Benzo[g,h,i]perylene Very strong retention for these analytes a shorter column is used for timely elution of the heavier PAHs. 3 1

19 PCB Congener Standard, Biphenyl thru Deca #0 #1 #3 #15 #10 #30 #54 #104 #3 #155 #12 # #1 SPB-Octyl #202 #19 #20 #19 #194 #20 #209 Nonpolar, shape selective phase #0 #1 #10 #3 #104 #15 #3 #30 #54 #155 #1 SP-2331 Polar, cyanosilicone phase #202 # #20,19 #20 # #0 #1 #30 #10 #3 #155 #1 #104 #54 #15 #3 #202 #20 # #209 SLB-IL2 Ionic liquid phase #19 #194 #12 #209 #19 #20 #194 Heaviest congener (decachlorobiphenyl) Not as well retained on polar phases Similar polarity to SP-2331, different selectivity See appendix 3 for congener names and run conditions 3 Conclusions 3 Ionic Liquids are different than traditional polymer GC phases Not susceptible to same stability issues as siloxane and PEG based phases More parts to change thus more possible chemistries possible selectivity Higher temp. limit than traditional phase of comparable polarity Ionic Liquids extend the polarity range of GC phases SLB-IL111 more polar than any traditional phase SLB-IL0 Ionic Liquid Phase offers Improved inertness over SLB-IL59 Complimentary selectivity to PEG phases Higher maximum temperature than PEG phase Lower bleed than PEG phases Can be used for a wide variety of applications 19

20 Acknowledgements Prof. Daniel Armstrong, U. Texas Arlington Prof. Luigi Mondello, U. Messina, Messina, Italy Supelco R&D Team Our customers worldwide 39 Thank You 40 sigma-aldrich.com/il-gc 20

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