Analytical Method for Determining the Total Content of Methyl Benzimidazole Carbamate Fungicides in Water by Column Switching Liquid Chromatography Mass Spectrometry

Abstract

An analytical method for determining the total content of fungicides carbendazim (MBC, methyl benzimidazole-2-yl-carbamate), benomyl (methyl l-(butylcarbamoyl)benzimidazole-2-yl-carbamate) and thiophanate-methyl (dimethyl 4,4'-(o-phenylene)bis(3-thioallophanate)) in water has been developed. The latter two are known to be converted to MBC in the environment. A water sample (100 ml) was mixed with potassium dihydrogenphosphate and disodium hydrogenphosphate (pH 6.8�0.2) and then refluxed for 1 h. By this reaction the fungicides were quantitatively converted to MBC. An aliquot (10 ml) of the reaction mixture was injected into a high-performance liquid chromatograph equipped with a column-switching apparatus and a thermospray mass spectrometer. The detection limit was 0.02 ppb equivalent as MBC. The recoveries of benomyl, carbendazim and thiophanate-methyl fortified in water at a fortification level of 0.05 ppb ranged from 85 to 95%. © 1992, The Japan Society for Analytical Chemistry. All rights reserved.