Chromatograms of Foods for Multicomponent Residue Determination of Pesticides Containing Phosphorus and/or Sulfur by GLC with Flame Photometric Detection

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Abstract
As part of an effort to devise a multicomponent pesticide residue analysis, temperature programmed gas chromatography with the Melpar flame photometric detector was used to obtain chromatograms of extracts of 39 repsentative foods on the thermally stable OV-101 and OV-210 packings. The chromatograms, which show where interference occurs with each food, supplement data previously reported on the retention times of 138 pesticides and metabolites containing phosphorus and sulfur in their molecules. Thus, where interferences from a food are absent, observation of pesticide peaks is possible. Food samples were extracted by one of 4 methods and then partitioned between hexane and acetonitrile by one of 2 procedures prior to analysis by gas chromatography. Very little interference was seen in the chromatograms of about 90% of the food extracts in the P mode and about two-thirds of the food extracts in the S mode; except for high fat samples, weights of co-extractives were also generally small. The lower limit of detection for most pesticides was estimated to be 0.01–0.05 ppm in the P mode and 0.02–0.1 ppm in the S mode. Analysis using the S mode has limited applicability because of the large samples needed to offset the lesser sensitivity of the S detector and the resulting contamination of the chromatographic column by coextractives. Analysis using the P mode is considered practical now. Retention time data on 8 additional pesticidal compounds are also reported.

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