Quantification of Phorate in Agricultural and Biological samples by Spectrophotometric method

A simple and sensitive spectrophotometric method for the quantification of phorate (organophosphorus insecticide) is described. The method is based on the oxidation of phorate insecticide with a slight excess of N-bromosuccinimide (NBS) and the unconsumed NBS was determined with crystal violet on a spectrophotometer at λmax 555nm. Beer’s law was obeyed in the concentration range of 0.10 to 0.40 ppmwith the limit of detection (LOD) as low as 0.05 ppm. The molar absorptivity and Sandell’s sensitivity of the method were found to be 2.68×106 mol-1 cm-1, and 0.7×10-5µgcm-2, for phorate insecticide respectively. The method was successfully applied for the quantification of phorate in various Agricultural and Biological samples. Statistical analysis of the results indicates that the method is precise and accurate.This method is free from the interference of common ions and other pesticides. The reliability of the method was checked by parallel determination against the reported method. In the absence of sophisticated equipment like HPLC and GLC, the proposed method can be used for pesticide residue analysis.