Development of a simple method for the detection of residues of phosphorus insecticides

The aim of this study was to detect the residues of phosphorus pesticides whether they are in fruits and in vegetables. For this reason, an available detection method was devoleped by using pesticides standards. At first phosphomolybdate was formed by using standard phosphate solutions and ammonium molybdate and then it was reduced to obtain molybdenum blue. According to the earlier experiments, m-phenylenediamine, which hadn?t been used classically as a reductant, was tested and at the first part of this study a phosphate detection method was developed by using this reductant. The optimum pH range was found for the reduction of phosphomolybdate as 1-1,5 and as 5-6 for the formation of molybdenum blue. The maximum absorbance was measured between 705 nm and 710 nm and the molar absorbtivity coefficient was calculated in terms of phosphorus as 2,95x10-3 L/mol×cm.At the second part of this study, developed method was used for the determination of two pesticides, dimethoate and methyl parathion. Before reacting with ammonium molybdate, pesticides were degraded in alkaline conditions with hydrogen peroxide to form phosphate. Although the the aim of this study was qualitative determination, a quantitative determination was also achieved approximately.