Assessment and validation of the p-QuEChERS sample preparation methodology for the analysis of >200 veterinary drugs in various animal-based food matrices

The need remains for veterinary multi-residue methods that reliably quantify and identify veterinary drugs in the various animal-based food matrices. Such a method should not only show good method performance parameters (e.g. recoveries of analytes) but must also be fast and cheap. The proposed method focused on the following points: acceptable analyte trueness (recovery) and precision for a large number (200) of diverse veterinary drugs in the relevant animal-based food matrices (egg, muscle, fatty fish, liver, kidney, and honey). The sample preparation method termed p-QuEChERS uses a salt mixture consisting of potassium phosphates to induce phase separation. The avoidance of conventional QuEChERS salts (e.g. magnesium sulphate) significantly improves recoveries of several critical analytes. Analyte recoveries were further improved by adding a centrifugation and a defatting step before initiating the salt-induced phase separation. This combined clean-up removes a large fraction of the potentially interfering matrix compounds. As a result, matrix effects in the electrospray interface were minimized. These factors were the basis for the obtained good validation data. Two types of high-resolution mass spectrometers coupled to liquid chromatography were compared for analysis. In comparison with conventional QuEChERS, the proposed p-QuEChERS concept improved the recovery of polar analytes such as penicillins, tetracyclines and quinolones. The simplicity of the procedure and the low consumable expenses make the method ideal for the routine control of veterinary drugs in all evaluated animal-based food matrices.