Evaluation of new stationary phases for the separation of fatty acid methyl esters

In the analysis of fatty acids, one of the most commonly used tools is a GC separation of the fatty acid methyl esters (FAME). Many researchers perform this separation using a non-polar phase such the ubiquitous 5 pkenyl / 95 methyl capillary columns found in most every chromatography laboratory. Numerous laboratories have also turned recently to polar phases such as 70 cyanopropyl columns, as this type of chemistry provides increased selectivity for unsaturated compounds, and thus improved separation of cis/trans and omega(3)/omega(6) FAME isomers. Here, a series of columns nominally having 60, 70, 80, and 90 bis-cyanopropyl content have been tested for the separation of FAME isomers. Trends in retention and the influence of increasing phase polarity on effective and fractional chain lengths are highlighted to provide the FAME chromatographer with insight into which of these novel stationary phases might be best suited to their particular application. In addition, the elution temperatures (T-e) of the FAME and linear alkane standards are presented, as this information will be of value to comprehensive two-dimensional multidimensional GC (GC x GC) users who wish to use these columns in the primary dimension separation.