Abstract
Preparative gel permeation chromatography of ethyl acetate extracts of Southern Pea vines precedes the simultaneous quantitation by electron capture gas chromatography of chlorpyrifos [0,0-diethyl O- (3,5,6-trichloro-2-pyridyl)-phosphorothioate] and its major metabolite 3,5,6-trichloro-2-pyridinol, which is analyzed as its iV,0-bis(trimethylsilyl)acetamide derivative. The dark green extract of a pea vine sample (spiked with both the pesticide and its metabolite) is concentrated and chromatographed on a Bio-Beads S-X3 column. Fractions are monitored for cleanup effectiveness by measuring the absorbance at 490 nm and also by gas chromatographic analysis for chlorpyrifos and 3,5,6-trichloro-2-pyridinol recovery. Results showed that the pesticide and its metabolite are separated from the bulk of optically absorbent compounds. Recoveries from 25 g spiked pea vine samples, cleaned up on the Bio-Beads column, are 100% at levels of 0.2 ppm (5 μg) and above, and 62% at levels ranging from 0.01 (0.25 μg) to 0.2 ppm. This analytical procedure provides a fast, sensitive method for simultaneous quantitation of these compounds which were previously determined by 2 separate procedures.
