QuEChERS-based extraction with dispersive solid phase extraction clean-up using PSA and ZrO2-based sorbents for determination of pesticides in bovine milk samples by HPLC-DAD.

In this study, a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction technique was adapted to develop a simple sample treatment for multi-residue pesticide analysis in milk samples. The proposed method is based on liquid-liquid partitioning with acetonitrile followed by dispersive solid phase extraction clean-up using primary secondary amine along with zirconia-coated silica particles for extract purification. Identification and quantification of 30 pesticides was conducted via high performance liquid chromatography with diode-array detection (HPLC-DAD). Recoveries were from 70 to 100% for the vast majority of the analytes, with relative standard deviations less than 20% being observed. HPLC-DAD provided suitable linearity, precision and accuracy. For 28 of 30 analytes in the study method limit of quantification values (mLOQs) comply with the most recent European Union guidelines for the maximum residue levels (MRLs) in milk. Negligible matrix effect was observed due to efficient extract clean-up with ZrO2-based sorbents.