Quantitative Aspects of Isothermal and Programmed Temperature Gas Chromatography of Fatty Acid Esters and a Practical Lower Limit of Detection

Abstract

This study was initiated to define the importance of temperature and retention volume in quantitative gas chromatography with thermal conductivity detectors (TCD) and flame ionization detectors (FID). Optimum temperature and optimum retention volume increase with molecular weight for the C₁₂ to C₂₈ saturated esters. It is demonstrated that relatively large amounts of very long chain methyl esters would be undetected by present optimum isothermal methods for the usual fatty acids reported. The shape of gas chromatographic peaks is correlated with the linear range of detector response as a basis for a limit of detection. The limit of detection varies logarithmically with molecular weight in isothermal analysis. However, by using optimum programmed temperature gas chromatographic (PTGC) techniques, the limit of detection increases slowly with molecular weight and increased retention volumes.