Salt-induced Homogeneous Liquid-liquid Microextraction as a Rapid Clean-up and Preconcentration Technique for Chromatographic Determination of Diazinon and Cypermethrin in Milk Samples

Herein, a convenient, simple, rapid, labor efficient and economical salt-induced homogeneous liquid-liquid microextraction technique coupled with high-performance liquid chromatography-photo diode array detection system was developed for sample preparation, extraction and quantitative determination of diazinon and cypermethrin in milk samples. In a single step, a homogeneous solution containing acetone and dichloromethane was used for the extraction of analytes and precipitation of milk proteins. This solution was broken by the addition of sodium chloride as a phase separator agent. Several variables affecting the extraction efficiency such as composition of homogeneous solution, concentration of phase separator agent and extraction time were fully evaluated and optimized. Under optimal conditions for analysis of two pesticides, matrix-matched calibration curves with dynamic linear ranges of 0.065-1300 μg l-1, limit of detection of 0.018-0.03 μg l-1, and the limit of quantification of 0.065-0.1 μg l-1 were obtained. The enrichment factors and extraction recoveries were 158-174 and 79-87%, respectively. Precision and accuracy of the method based on RSDs and REs for three concentration levels of both pesticides were achieved between 2.7-12.3% and 6.1-8.3% (n = 5), respectively. The represented method was successfully applied for the simultaneous assay of diazinon and cypermethrin in different milk samples.