Residue analysis of onions and other foodstuffs with a complex matrix using two-dimensional capillary-GC with three selective detectors

Summary

Pesticide residue analysis in food is mainly performed by multimethods. In Germany, multimethod S 19 of the DFG pesticide commission is in widespread use. Applying this method to onion and leek samples, GC-ECD analysis becomes very difficult as most of the pesticide peaks are overlapped by matrix compounds. Two-dimensional capillary-GC using the techniques of heart-cutting and backflush makes it possible to transfer small fractions or even single peaks to a second column where all relevant pesticides can be separated from their overlapping matrix compounds. Nitrogen and phosphorus containing pesticides in onion and leek samples are identified by selective detectors (NPD, FPD) without any problem.