Residue Analysis of Acaricide Hexythiazox in Crops

Abstract

Two analytical methods of determining the residual amounts of hexythiazox [trans-5-(4-chlorophenyl)-N-cyclohexyl-4-methyl-2-oxothiazolidine-3-carboxamide; HTZ] and its metabolites, PT-1-2, PT-cy-OH PT-cy-O in crops were investigated. One is the HTZ analytical method for HTZ only and the other the total method for HTZ and its metabolites. By the HTZ method, HTZ was extracted with methanol and purified through liquid-liquid separation and column chromatography, followed by HPLC determination. By the total method, HTZ and its metabolites were extracted with methanol and converted to a decyclohexylaminocarbonyl derivative (PT-1-3) through alkali hydrolysis, followed by column chromatography and HPLC determination. The detection limit by both methods was 0.01ppm and the fortified recovery was more than 80%. Residue analyses of nine crops (12 matrices) suggested that there was no difference in residual amount between both methods. HTZ made up most of the residue in crops and its metabolites were negligible in amount. The results showed that the HTZ analytical method, which is simple and quick, is more suitable. GC was also effective in determining the residual amount of HTZ and its metabolites.