Screening methods for asulam, oxine-copper and thiram in water by high-performance liquid chromatography after enrichment with a minicolumn

Abstract

A syringe-type minicolumn containing 40 μl of C 18 bonded silica was used for pretreatment of the samples in the determination of methyl-N-(aminophenylsulphonyl)carbamate (asulam), bis(8-quinolinolato)copper (oxine-Cu) and bis(dimethylthiocarbamoyl)disulphide (thiram) in ground, tap and river water by reversed-phase high-performance liquid chromatography (HPLC). The low levels of pesticides were adsorbed on the minicolumn, which was then connected to the injector of the HPLC system, and directly injected into the loop by eluting with a small amount of eluent. Average recoveries of asulam, oxine-Cu and thiram in water samples at concentrations of 5 μg/l were 91.5, 77.1 and 87.3%, respectively. The detection limits of asulam from 300 μl of water sample and of oxine-Cu and thiram from 1 ml were 0.2, 1.0 and 0.5 μg/l, respectively. It took only about 10 min to obtain a chromatogram on HPLC, including sample pretreatment. The syringe-type minicolumn was useful to eliminate compounds coexisting in water. This small-scale procedure enabled the sample volume required and the amount of organic solvent for elution to be reduced.