A dual validation approach to detect anthelmintic residues in bovine liver over an extended concentration range

This paper describes a method for the detection and quantification of 38 residues of the most widely used anthelmintics (including 26 veterinary drugs belonging to the benzimidazole, macrocyclic lactone and flukicide classes) in bovine liver using two different protocols for MRL and non-MRL levels. A dual validation approach was adopted to reliably quantify anthelmintic residues over an extended concentration range (1–3000 μg kg−1). Sample extraction and purification was carried out using a modified QuEChERS method. A concentration step was included when analysing in the low μg kg−1 range. Rapid analysis was carried out by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS), which was capable of detecting residues to <2 μg kg−1. The method has been single-laboratory validated according to the 2002/657/EC guidelines and met acceptability criteria in all but a few cases. The inclusion of 19 internal standards, including 14 isotopically labelled internal standards, improved accuracy, precision, decision limit (CCα) and detection capability (CCβ).