Carboxylesterase from edible legume seeds and their sensitivity to organophosphate and carbamate pesticides

Carboxylesterase from edible legume seeds, including black gram bean (Vigna mungo (L.) Hepper), mung bean (Vigna radiata (L.) Wilczek) and red bean (Vigna umbellata (Thunb.) Ohwi and Ohashi) has been partially purified using the ammonium sulphate salting-out procedure. The specific activity of the partially purified carboxylesterase extracted from black gram bean, mung bean and red bean are 3.96±0.26, 1.51±0.10 and 1.29±0.08 U/mg, respectively (p<0.05). The carboxylesterase from black gram bean showed very high sensitivity to 24 types of organophosphate pesticides (OPs) and 7 types of carbamate pesticides (CAs) at the concentrations of 0.001-3.0 µg/ml. The limit of detection (LOD) obtained for OPs and CAs pesticide residues were 0.002 and 0.01 mg/kg, respectively. For performance assessment of methods for pesticide determination in vegetables, all performance parameter values, including sensitivity, accuracy, and specificity of the carboxylesterase enzyme inhibition method, are 100% compared with commercial pesticide test kits and are 70.5%, 90%, and 100%, respectively, compared with chromatographic method analysis.