Evaluation of Use of a Dicationic Liquid Stationary Phase in the Fast and Conventional Gas Chromatographic Analysis of Health-Hazardous C_(18) Cis/Trans Fatty Acids

摘要

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 (mu)m 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 velence 5) were good, with RSD values lower than 0.07percent and 6.6percent, 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_(18:3(DELTA))~(9c,12c,15c), was subjected to analysis using C_(13:0) as an internal standard.