Development of an analytical method for multi-residue quantification of 18 anthelmintics in various animal-based food products using liquid chromatography-tandem mass spectrometry

In this study, we developed a simple screening procedure for the determination of 18 anthelmintics (including benzimidazoles, macrocyclic lactones, salicylanilides, substituted phenols, tetrahydropyrimidines, and imidazothiazoles) in five animal-derived food matrices (chicken muscle, pork, beef, milk, and egg) using liquid chromatography-tandem mass spectrometry. Analytes were extracted using acetonitrile/1% acetic acid (milk and egg) and acetonitrile/1% acetic acid with 0.5 mL of distilled water (chicken muscle, pork, and beef), and purified using saturated n-hexane/acetonitrile. A reversed-phase analytical column and a mobile phase consisting of (A) 10 mM ammonium formate in distilled water and (B) methanol were used to achieve optimal chromatographic separation. Matrix-matched standard calibration curves (R≥0.9752) were obtained for concentration equivalent to ×1/2, ×1, ×2, ×3, ×4, and ×5 fold the maximum residue limit (MRL) stipulated by the Korean Ministry of Food and Drug Safety. Recoveries of 61.2–118.4%, with relative standard deviations (RSDs) of ≤19.9% (intraday and interday), were obtained for each sample at three spiking concentrations (×1/2, ×1, and ×2 the MRL values). Limits of detection, limits of quantification, and matrix effects were 0.02–5.5 μg/kg, 0.06–10 μg/kg, and −98.8 to 13.9% (at 20 μg/kg), respectively. In five samples of each food matrix (chicken muscle, pork, beef, milk, and egg) purchased from large retailers in Seoul that were tested, none of the target analytes were detected. It has therefore been shown that this protocol is adaptable, accurate, and precise for the quantification of anthelmintic residues in foods of animal origin.