Multiresidue analysis of pesticides in peanuts using modified QuEChERS sample preparation and liquid chromatography-mass spectrometry detection

A multiclass method has been optimized and validated for the simultaneous determination of 113 pesticide residues belonging to several classes in peanuts. It has been based on the QuEChERS methodology (quick, easy, cheap, effective, rugged and safe) and ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). Several extraction solutions were tested and the composition that showed the best results consisted of a mixture of ethyl acetate and acetonitrile. A cleanup step using the dispersive phases C18 (octadecyl) and PSA (Primary and Secondary Amine) was necessary due to the high amount of oil present in the matrix. The method was validated and the parameters of validation were satisfactory. The accuracy was assessed by calculating the recovery of spiked blank samples in four concentration levels (0.010; 0.025; 0.050 and 0.100 mg kg(-1)). The results showed satisfactory recoveries (between 70 and 120%), except for oxamyl and tricyclazol at the 0.010 mg kg(-1) level that did not show acceptable parameters for the recovery assays. Repeatability and intermediate precision showed coefficients of variation <20%, except for buprofezin, etione and picolinafen at the 0.100 mg kg(-1) level. Limits of detection and quantification of the method were 0.005 and 0.010 mg kg(-1), respectively, except for oxamyl and tricyclazol.