Evaluation of Use of a Dicationic Liquid Stationary Phase in the Fast and Conventional Gas Chromatographic Analysis of Health-Hazardous C₁₈ Cis/Trans Fatty Acids

Abstract

The present research is focused on the evaluation of one 0.10 mm i.d. and two 0.25 mm i.d., ionic liquid (IL) stationary phase [1,9-di(3-vinyl-imidazolium) nonane bis(trifluoromethyl) sulfonyl imidate] columns, with lengths of 12 (the microbore capillary), 30 and 100 m, in the GC analysis of cis/trans fatty acid methyl esters (FAMEs). The selectivity of the IL columns toward a series of standard C(18:1), C(18:2), and C(18:3) geometric isomers (a group of 22 compounds was subjected to GC analysis) was compared to the performance of a widely used column in the cis/trans FAMEs analysis field, viz., a 100 m x 0.25 mm i.d. capillary with a 0.20 microm stationary phase film of bis-cyanopropyl polysiloxane (SP-2560). The selectivity provided by the IL phase was superior if compared to that of the other well-established capillary. An optimized IL method, using the longer column, was subjected to validation: retention time and peak area intraday precision (n = 5) were good, with RSD values lower than 0.07% and 6.6%, respectively; LODs (considering a S/N of 3) for C(18:1Delta)(9tr) and C(18:2Delta)(9tr,12tr) were 0.15 (7.3 ppm) and 0.18 ng (9.1 ppm) on-column, respectively, while LOQs (considering a S/N of 10) were 0.49 (24.3 ppm) and 0.60 ng (30.2 ppm), respectively; the method was found to be linear, for both trans FAMEs, in the 10-2000 ppm range. For the evaluation of accuracy, a hydrogenated margarine, spiked with known amounts of C(18:3Delta)(9c,12c,15c), was subjected to analysis using C(13:0) as an internal standard.

Gas Chromatographic Separation of Docosenoic Acid Positional Isomers on an SLB-IL100 Ionic Liquid Column

“…2 shows the plots of the ECL values against positional isomers observed on the SLB-IL100 and polymer phase columns at 180℃. The highest ECL values on the SLB-IL100 are consistent with the higher polarity of the SLB-IL100 compared to those of polymer columns [5][6][7][8] . The plots of the ECL values for 22:1n-11 to 22:1n-7 were paral- lel among the five columns ( Fig.…”

“…This column contains an ionic liquid stationary phase characterized by low column bleed, high thermal stability, and much higher polarity than that of traditional polymer stationary phases 5,6) . This column has been reported to successfully separate 18:1 cis/trans fatty acids 7,8) . The authors recently achieved the complete separation of six positional isomers of 20:1n-15 to 20:1n-5 including 20:1n-13 and 20:1n-11 on a 60-m column 9) .…”

Evaluation of ionic liquid stationary phases for one dimensional gas chromatography–mass spectrometry and comprehensive two dimensional gas chromatographic analyses of fatty acids in marine biota

“…Polar ionic liquid phases were used for the analysis of fatty acid methyl esters [32][33][34], and their potential for the separation of eicosenoic acid (C20:1) isomers [35] and octadecenoic acid (C18:1) and octadecadienoic acid (C18:2) isomers [36] was demonstrated. For these applications, flame ionization detection (FID) was used.…”

Theory and Practice of UHPLC and UHPLC–MS

“…To fully separate such a variety of compounds and geometrical and conjugated FA isomers, rather long (up until 100 m) and high-polarity columns are required, such as the bis-cyanopropyl polysiloxane phase (Christie, 2003) or the novel ionic-liquid (IL) phase (Ragonese et al, 2009). Furthermore, although the use of the MS detector with the support of linear retention indices (LRI) has proven useful for peak identification, the confirmation of FA identity can still be a cumbersome task because of the very similar mass spectra of the isomers.…”