Bulletin of the Chemical Society of Ethiopia

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Development of an indirect spectrophotometric method for determination of methamidophos insecticide in soil, water and vegetable samples

J. Shah, M. R. Jan, M. Muhammad, B. Ara, I. U. Rehman


A simple and rapid indirect spectrophotometric method for determination of methamidophos in water, soil and vegetable samples has been described. Methamidophos reacts with acid produced from p-dimethylaminobenzaldehyde (p-DMAB) as a result of Cannizaro’s reaction. The resultant adduct undergoes condensation reaction in acidic medium forming a yellow colored product. Absorbance of the colored product was measured at 405 nm and pH 3 against a reagent blank. The Beer’s law range is obeyed in the range 1-30 µg mL-1 with molar absorptivity of 2.8 ×103 L mol-1 cm-1. The limit of detection and quantification were found to be 0.20±0.03 and 0.60±0.04 µg mL-1 respectively. The proposed method was effectively applied for determination of methamidophos in various samples with percent recoveries in the range of 96±0.08 to 102±0.06 %.


KEY WORDS: Spectrophotometric, Methamidophos, p-Dimethylaminobenzaldehyde (p-DMAB), Cannizaro’s reaction


Bull. Chem. Soc. Ethiop. 2015, 29(2), 311-318

AJOL African Journals Online