Comparison of Extraction Techniques by Matrix Solid Phase Dispersion and Liquid-Liquid for Screening 150 Pesticides from Soil, and Determination by Gas Chromatography

Interest in the determination and screening of pesticide residues in soil is caused by widespread use of chemical pesticides in agriculture, which increase soil contamination. Two extraction techniques, matrix solid phase dispersion (MSPD) and liquid-liquid extraction (LLE) of residual pesticides (acaricides, insecticides, herbicides, and fungicides) from soil were compared. Advantages and disadvantages of both approaches were discussed. Pesticides from different chemical classes (organohalogen, organophosphorus, carbamates, pyrethroids, strobilurines, triazoles) were quantified by GC with a dual system detection – electron capture (EC) and/or nitrogen-phosphorus (NP). The MSPD was validated by comparing it with conventional LLE. Recovery studies were carried out at three levels: 1) ranged between 0.005-0.05 mg/kg, 2) 0.05-0.5 mg/kg, and 3) 0.25-2.5 mg/kg and average recoveries obtained for these compounds ranged from 72.4 to 120% for MSPD and 70.6-120% for LLE with relative standard deviations (RSDs) below 20%. Both methods were linear over the range assayed, 0.005-2.5 mg/kg. The uncertainties of the analytical methods were lower than 25.6% and 30%, with and without recovery correction, respectively. The rapid and practical MSPD technique has found a particular application in determining 147 pesticide residues of different physicochemical properties in soil with satisfactory validation parameters. The study estimated that MSPD has significant advantages over LLE because, coupled with simultaneous stage of purification, it allowed for a radical reduction time of analysis and its cost. MSPD fulfilled the requirements of multiresidue techniques. The method is reliable and can be useful for routine monitoring in soil.