Determination of Diazinon Pesticide in Water Using Continuous Solvent Extraction - Steam Distillation


A continuous solvent extraction-steam distillation method of water by heavier solvents was used for the extraction of diazinon pesticide, locally widely used, in aqueous samples involving the optimal conditions for extraction with chloroform or dichloromethane as extractor. The recovery for a concentration about 10 mg.L-1 of diazinon approaches to 100% using acidification of the water sample (pH=1.5-2) and a extraction- distillation time of 3.5 hour for an aqueous sample 500 ml with 150 ml of chloroform or dichloromethane as extractor. One extraction with small volumes of chloroform or dichloromethane, diazinon could be recovered to the extent of 70-78 % in the range 1-10 mg . L-1 . A UV- spectrophotometric method has been used for the determination and analysis of diazinon using 1cm quartz cells. The accuracy and precision of the method were determined by preparing laboratory samples of diazinon , the results showed relative error ranging from ± 0.2 to 4.8 % and the Relative standard deviation did not exceed 8.19 %. This method is simple and could be implemented with relatively low-coast equipment which is already available in chemical laboratories and it may be applicable to a wide range of aqueous samples.