Evaluation of Capillary Gas Chromatography for Pesticide and Industrial Chemical Residue Analysis. I. Comparison of Retention Ratios Obtained on Methyl Silicone-Coated Capillary Columns with Published Values for Packed Columns

Abstract

Many residue laboratories use the retention ratio data compiled by the Food and Drug Administration in its Pesticide Analytical Manual (PAM) for the tentative identification of pesticide and industrial chemical residues detected in food samples. These data were compiled using packed gas chromatographic columns. A study was undertaken to determine if these retention ratios could be used when applying capillary gas chromatography to residue analysis. Retention ratios of a selected group of 108 of the materials listed in the PAM tables were determined isothermally with split injection on 4 WCOT capillary columns obtained from 3 commercial suppliers and coated with 4 different methyl silicone coatings. Of the tested reference materials, 90 displayed retention ratios that matched the PAM values on all columns, 10 differed on at least one of the 4 columns, and only omethoate and monocrotophos gave retention ratios differing on all 4 columns.

Effective application of the relative retention time diagram for gas chromatographic analysis of pesticides

“…On the other hand, the majority of the FDA's retention time ratios obtained in packed columns can be used for the tentative identification of pesticides by using capillary columns at isothermal conditions for the four coatings tested in their papers (Fehringer and Walters, 1984).…”

“…Simultaneous determination of organophosphorus pesticides was reported by FPD-GC with capillary columns (Tonogaietal., 1990). Also, most of the RRT data for pesticides compiled using packed columns matched Fehringer's data using capillary columns (Fehringer and Walters, 1984), so our RRT data would be used with capillary gas chromatography. Therefore, the RRT diagram could be evaluated as an effective tool for GC analysis.…”

“…Chlorpyrifos was used as a reference compound for comparison with the data in other papers (Fehringer and Walters, 1984;Saxton, 1987;Pesticide Analytical Manual, 1987).…”

“…As chlorpyrifos consists of Cl, P, S, N, C, and H atoms, it has wide sensitivity to several kinds of detectors such as flame ionization detector (FID), flame photometric detector (FPD), flame thermionic detector (FTD), and electron capture detector (ECD) of GC. This chemical is also used as a reference compound in other papers (Fehringer and Walters, 1984;Saxton, 1987; Pesticide Analytical Manual, 1987).…”