Development of a Straightforward and Cheap Ethyl Acetate Based Method for the Simultaneous Determination of Pesticides and Veterinary Drugs Residues in Bovine Liver and Muscle

The optimization and validation study of a qualitative and quantitative multiclass, ethyl acetate (EtOAc) multi-residue method to straightforward monitor 48 compounds in liver (6 veterinary drugs and 42 pesticides) and 54 in muscle (5 veterinary drugs and 49 pesticides) followed by high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) and gas chromatography mass-spectrometry determination (GC–MS) is presented. Several clean-up sorbents were evaluated looking for the best strategy for the removal of the matrix co-extractives. A combination of aluminium oxide, (Al₂O₃), C-18 and magnesium sulphate (MgSO₄) yielded the best analytical results in terms of precision and accuracy. The method was validated at three fortification levels: 10, 100 and 250 µg kg⁻¹. The percentages of recovery were between 70 and 114 % for bovine muscle and 70–118 % for liver. Repeatability and intermediate precision percentages were below 20 % for both matrices. Most of the compounds under study presented good linearity and quantification limits below their corresponding European Union (EU) and Codex Alimentarius maximum residue levels (MRLs). Twenty-two randomly taken real samples were analyzed with the validated methodology, trying to prove its effectiveness and suitability for routine analysis. The validated methodology represents a fast and cheap alternative for the simultaneous analysis of pesticides and veterinary drugs which can be easily extend to other compounds and matrices.