Multi-residue Determination of Veterinary Drugs in Fishery Products Using Liquid Chromatography-Tandem Mass Spectrometry

The aim of the present study was to develop a multi-residue confirmation method for the analysis of veterinary drugs in fishery products using liquid chromatography-tandem mass spectrometry. The chosen veterinary drugs, which are legally authorized compounds in Korea, were categorized into chemical classes such as amphenicols, cephalosporins, fluoroquinolones, macrolides, penicillins, pleuromutilins, sulfonamides, and tetracyclines. Sample extraction and cleanup were evaluated based on a modified quick, easy, cheap, effective, rugged, and safe procedure using octadecylsilane and primary secondary amine sorbents for purification. Extractions were carried out using an ammonium acetate buffer and ethylenediaminetetraacetic acid disodium salt (pH 4.0) with the addition of ammonium formate in water/acetonitrile. Instrumental analysis was performed using positive/negative ionization in the multiple reaction monitoring mode. The chromatographic conditions were optimized to give run time of < 20 min, and the developed method was validated according to the Codex Alimentarius Commission guidelines. Mean recoveries of the veterinary drugs ranged from 68.1 to 111%. At all target concentrations, the intraday precision was < 15%, and the lowest limits of detection and quantification were < 5 and < 10 μg kg⁻¹. To evaluate the imprecision arising from residual matrix components, the linearity of our method was determined as > 0.98 using matrix-matched calibrations constructed at six different concentrations. The proposed method was applied to the analysis of 403 real samples obtained from domestic markets in Korea, and a number of samples tested positive (27.1%) for the targeted drugs. This analytical method is suitable for reliable detection of veterinary drug residues in fishery products.