High-throughput capillary gas chromatography for the determination of polychlorinated biphenyls and fatty acid methyl esters in food samples

High-throughput capillary gas chromatography (CGC) methods, developed during the Belgian 1999 "dioxin" food crisis, for the determination of the contaminating polychlorinated biphenyls (PCBs) and the fatty acid composition of the lipids are described. For PCB analysis, the fat obtained by ultrasonic extraction is fractionated by matrix solid-phase dispersion, and the PCBs are analyzed by CGC-electron capture detection on a 10-mL × 100-μmi.d. HP-5MS column. Analytical conditions for the high-speed column are deduced from analyses on conventional CGC columns using the method translation software. The concept of retention time locking is implemented to facilitate the elucidation of the PCB markers. The fatty acid methyl esters (FAMEs) are prepared by the sodium methylate procedure on part of the ultrasonic extract followed by analysis on 10-mL × 100-μm-i.d. HP-WAX or BPX-70 capillary columns. By optimizing both the sample preparation and CGC analysis, the throughput is more than fifty PCB and FAME samples per day with the same robustness as conventional methods.