Article Title

Determination of benzoximate and allethrin residues in crops


High performance liquid chromatography (HPLC) and gas chromatography (GC) were developed to determine benzoximate and allethrin in crops. A residue of benzoximate was extracted with methanol/water solution from citrus fruits and partitioned into dichloromethane, which was then concentrated under reduced pressure, purified with a Sep-Pak Florisil cartridge, and finally determined by HPLC at UV 235 nm using a Lichrospher PR-18 column. A residue of allethrin was extracted with acetone-petroleum ether (1:2) from mushrooms. The extract was then washed with 2% aqueous NaCl, evaporated to dryness under reduced pressure, and reconstituted to volume prior to GC-ECD (electron capture detector) analysis. Recovery studies for benzoximate and allethrin were performed at 1~3 ppm and 1.5~4.5 ppm fortification levels, respectively. Average recoveries were 92.4~94.9% for benzoximate and 90.5~91.0% for allethrin. Coefficients of variation of which were 1.5~5.1%, and 1.5~1.6%, respectively. The detection limits of both benzoximate and allethrin were 0.05 ppm. When 10 citrus fruits and 10 mushrooms, which were purchased from traditional markets and supermarkets in Taipei between February and May of 1997, were analyzed, no benzoximate was detected in citrus fruits, while 2 mushroom samples contained 0.09 and 0.06 ppm allethrin were detected.

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