Improved Separation of Fame Isomers Using Comprehensive Two-Dimensional Gas Chromatography. Application to Broccoli Samples

A new method has been developed to separate 47 fatty acid methyl esters (FAMEs), including the linoleic and linolenic acid group of isomers, using comprehensive two-dimensional gas chromatography (GC×GC) coupled to a capillary flow technology-based modulator and flame ionization detector (FID). In addition a modification of the inverted phase, column combination was introduced, using a high polar column (BPX-70) in the first dimension and a semi-polar column (ZB-35) in the second. Moreover, the influence of the length of the second dimension column on FAME isomer separation was studied. When compared with previously published methods devoted to FAME analysis, separation was improved, both in terms of analysis time, and with regard to the number of FAMEs separated and identified in the same chromatographic run. Finally, the GC×GC-FID method proposed was successfully employed to identify FAMEs in supercritical fluid extracts from the leaves of three different broccoli cultivars (Naxos, Nubia, and Viola).