Analysis of pendimethalin residues in fruit, nuts, vegetables, grass, and mint by gas chromatography

Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], in t he formulation of Prowl (a commercial herbicide),was applied to various cro ps. Analysis of pendimethalin and its metabolite [4(1-ethylpropyl)amino-2-m ethyl-3,5-dinitrobenzyl alcohol] was accomplished by utilizing liquid-liqui d partitioning, gel. permeation chromatography (GPC) for nuts and mint, sol id-phase extraction (SPE) cleanup, and gas chromatography(GC) with a nitrog en-phosphorus detector (NPD). Method validation recoveries for fruits, nuts , vegetables, grass, and mint are given for both compounds. Pendimethalin a verage recoveries ranged from 71% to 126% over two levels of fortification. Pendimethalin metabolite average recoveries ranged from 69% to 123% over t wo levels of fortification. The quantitation limit for all crops except min t was 0.050 ppm. The quantitation limit for mint and mint oil was 0.10 ppm. Residues greater than the limit of quantitation were found for pendimethal in in apple pomace, fresh and dry fig, grass screenings, mint oil, almond h ulls, green onion,and tomato pomace (wet and dry). Residues greater:than th e limit of quantitation were found for pendimethalin metabolite in grass sc reenings, grass straw, and almond hulls. All other crop analyses for pendim ethalin and its metabolite were below the limit of quantitation.