Evaluation of capillary gas chromatography for pesticide and industrial chemical residue analysis. II. Comparison of quantitative results obtained on capillary and packed columns.

Results of pesticide and industrial chemical residue determinations, using both capillary and packed column gas chromatography (GC), in 3 Food and Drug Administration (FDA) laboratories have been compiled and compared. Samples consisted of food products collected for routine residue screening by the respective laboratories. Extracts were prepared by conventional multiresidue methodology. Capillary column systems and operating conditions were selected at the discretion of each laboratory and were therefore variable, although split/splitless injectors in the split mode were used with prescribed precautions in all cases. Packed column systems were operated as specified in the FDA Pesticide Analytical Manual (PAM). Overall correlation between the 2 systems, expressed as the average ratio of packed column result to capillary column result, was 0.99 for 120 determinations in 41 samples. The higher resolving power of the capillary systems allowed quantitation of several residues that were incompletely separated and therefore unquantifiable using the packed columns. Capillary column GC with the split injection technique, used with appropriate precautions, was found to be both reliable and advantageous for regulatory determination of pesticide and industrial chemical residues in foods and feeds.