Automated gas chromatographic analysis of pesticide residues in food samples by means of fused-silica capillary columns and data processing.

A conventional gas chromatograph with one system for split and splitless injection and one on-column injection system for fused-silica capillary columns and the two selective nitrogen-phosphorus and electron-capture detectors is applied to pesticide residue analysis in food samples. The gas chromatograph is equipped with a two-channel data processor that can be programmed with BASIC. Additionally an autosampler is used with the splitless injector. This automated injection system is connected to a 25-m methylsilicone fused-silica column which is coupled via an effluent splitter parallel to both detectors and used for screening in routine analysis. Calibration is performed on this column by means of three calibration test mixtures which include three internal standards. All compounds are calibrated on both detectors in parallel and the response calculated as an additional identification parameter. After the analysis of a of food samples together with the calibration mixture a report is plotted, containing all pesticide residues which may be present in the samples and their tentative quantities. The final confirmation is achieved on the second column, coated with methylphenyl-silicone phase, connected to the on-column injector.