The Effectiveness of Household Chemicals in Residue Removal of Methomyl and Carbaryl Pesticides on Chinese-Kale

Abstract

Leafy Chinese-Kale treated with methomyl and carbaryl was subjected to various chemical aqueous washes to determine the reduction of pesticides. All washing solutions, prepared from chemical stuffs available in household, consisted of 0.9% NaCl, 0.1% NaHCO₃, 0.001% KMnO₄ and 0.1% acetic acid. Filtrated water was used as control. After 15 min of washing procedure, the reduction of pesticide residues were determined by high-pressure liquid chromatography analysis and shown to have a lesser extent in methomyl compared to carbaryl. Methomyl also showed lower level of degradation in the washing solutions (2.6 to 21%) compared to carbaryl (20 to 62%). These may due to the difference of behavior and physiochemical properties between the pesticides. Variations in the degree of reduction in each pesticide were observed with the washing solution treatments. Among the washing solutions, the 0.001% KMnO₄ performed the most effective in residue reduction (48 and 93 % in methomyl and carbaryl, respectively). This may due to the oxidative property of this material. In 0.9% NaCl, 0.1% NaHCO₃ and 0.1% acetic acid washing solutions, the residue reductions were 39, 43 and 43% for methomyl; 91, 91 and 90% for carbaryl, respectively. In water, the reduction of methomyl and carbaryl were 38 and 88%, respectively. The results showed vegetable wash with solutions prepared from the chemical stuffs to be more effective in reducing pesticides than water alone.