Abstract
An analytical method for determining the total content of fungicides carbendazim (MBC, methyl benzimidazole-2-1yl-carbamate), benomyl (methyl 1-(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 (100ml) was mixed with potassium dihydrogenphosphate and disodium hydrogenphosphate (pH 6.8±0.2) and then refluxed for 1h. By this reaction the fungicides were quantitatively converted to MBC. An aliquot (10ml) 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 0.02ppb equivalent as MBC. The recoveries of benomyl, carbendazim and thiophanate-methyl fortified in water at a fortification level of 0.05ppb ranged from 85 to 95%.
