Gas-liquid chromatographic determination of fenvalerate insecticide residues in processed apple products and by-products.

Apples from trees treated in the field at 2-week intervals (9 foliar applications) with the synthetic pyrethroid insecticide fenvalerate (cyano(3-phenoxyphenyl) methyl 4-chloro-alpha-(1-methylethyl)-benzeneacetate) were processed into apple sauce, juice, pomace, and peels plus cores. Gas-liquid chromatographic analysis of the commodities for fenvalerate showed the sauce and juice to be essentially residue-free, the whole apples to contain about 0.4 ppm, and the pomace and peels plus cores to contain about 2 and 1.5 ppm, respectively. Agreement among 5 laboratories using modifications of the same basic method was good.