Simulation of fatty acid peak profile on a 100-m CP-Sil 88 column and application for analysis of commercial trans fat alternatives in Thailand

A program to simulate fatty acid peak profiles on a gas chromatograph coupled with a 100-m CP-Sil 88 column has been developed. The concept of a quantitative structure-retention relationship (QSRR) with a Gibbs energy additivity approach and Gaussian function was used to create the program, which can be performed on Excel spreadsheets. The present method is applicable for optimizing multi-step temperature-programmed gas chromatography (GC) for determination of fatty acid profiles in samples. Strong correlation coefficients were obtained between experimental and simulated retention times (tR), with R2=0.9981. Based on simulation results, the AOAC2012.13 GC condition was recommended for the trans fat analysis. The proposed method was applied to analyze fatty acid compositions in 12 samples of trans fat alternatives, including shortenings, margarines, butter blends and non-dairy creamers, sold commercially in Thailand. The major trans fatty acid (TFA) isomer found after fractionation on Ag-Ion SPE was C18:1t11 (trans-vaccenic acid). The samples contained 0.0–6.3 g TFA/100 g fat, which is similar to the level found in nature. Contents of TFA in the samples determined by GC after fractionation on Ag-Ion SPE were comparable to those obtained by Fourier transform infrared analysis.