Simplifying Fatty Acid Analyses in Multicomponent Foods with a Standard Set of Isothermal GLC Conditions Coupled with ECL Determinations

It is common to use some sort of temperature program in the analysis of fatty acid methyl esters. For samples that contain only a few components or in situations where all samples are basically the same, temperature programming can offer certain advantages. Unfortunately, samples such as these are certainly not the norm in routine food fatty acid analysis. A gas-liquid chromatographic column, the Carbowax-20M fused-silica phase (cross-linked) recommended by Ackman as a "standard" for fatty acid analysis (it simplifies the work and reduces the chance for errors), is used to chromatograph mixtures of methyl esters at column temperature settings that range from 170°C to 250°C. It is determined that three specific temperatures (183°C, 212°C, and 247°C) permit complete resolution of a wide array of acids under strictly isothermal conditions. Equivalent chain length values have been compiled for use in assigning identities of fatty acid methyl esters. Also, the specific responses of individual methyl esters to alterations in column temperature can be of use in the identification of peaks in complex mixtures.