Automated dual-cartridge solid-phase extraction method for multi-residue determination of veterinary drugs in bovine muscle, liver, fat, and milk

Solid-phase extraction (SPE) is a widely used sample preparation technique for the determination of veterinary drug residues in foods due to its effectiveness in removing matrix components. However, conventional SPE methods are often time consuming and labor intensive. In this study, we developed an automated sample preparation method employing a dual-cartridge SPE system for the multi-residue determination of veterinary drugs in bovine-derived food matrices. The method integrates two C18 cartridges connected in series, with controlled water addition between cartridges to improve cleanup efficiency. Analytical performance was evaluated for 52 veterinary drugs in bovine muscle, liver, fat, and milk at a concentration of 0.01 mg kg^-1. Minimal matrix effects were observed, allowing for accurate quantification using solvent-based calibration without the need for matrix-matched standards or isotope-labeled internal standards. Satisfactory analytical performance was obtained for approximately 80% of the analyte-matrix combinations, with trueness values ranging from 70% to 120% and intra- and inter-day precision values within 25% and 30%, respectively, although some combinations fell outside these criteria due to degradation or matrix effects. The method also demonstrated high selectivity, with no interfering peaks detected near the retention times of target analytes. Overall, the developed automated SPE method provides a robust and reliable platform for quantification of veterinary drug residues in complex bovine-derived food products, supporting its suitability for use in routine food safety monitoring and regulatory surveillance.