Evaluation of a modified QuEChERS method for extraction of diazinon and edifenphos from two paddy soils using HPLC-UV

In this research, the efficiency of diazinon and edifenphos extraction from two paddy soils with different organic contents was investigated using a modified QuEChERS extraction method. The methods included extraction of 10 g soil using acetonitrile with or without the addition of water to the samples, extraction of 5 g soil using acetonitrile with the addition of water to the samples, and extraction of 5 g soil using ethylacetate with the addition of water to the samples. The clean-up was carried out using dispersive solid phase extraction (dSPE). The pesticides quantification was performed using a liquid chromatography system equipped with a UV/VIS detector. According to the results, soil organic matter contents affected the recoveries of the two pesticides significantly. Factors such as reducing the sample size to 5 g, hydrating of the samples prior to extraction, and using ethylacetate as the solvent increased the extraction efficiencies of the two pesticides significantly. Best recoveries (70-100%) and relative standards deviations (RSDs) (˂20%) were achieved using 5 g soil as the sample with the addition of water and extraction using ethylacetate. The method had a good linearity within the range of 0.5-10 µg g-1. The sensitivity of the method was confirmed by the estimated method detection and quantification limits between 0.07-0.54 µg g-1.