Evaluation of QuEChERS Sample Preparation for Determination of Avermectins Residues in Ovine Muscle by HPLC-FD and UHPLC-MS/MS

A fast and sensitive method using high performance liquid chromatography-fluorescence detection (HPLC-FD) and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed and validated for the determination of avermectins residues in ovine muscle samples. QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation based on acetonitrile extraction followed by partitioning with NaCl and Na2SO4 and dispersive solid-phase extraction (d-SPE) clean-up with C18 was applied. Na2SO4 was used instead of MgSO4 due to lower amounts of co-extractives in the final extract. The procedure was validated according to the Commission Decision 2002/657/EC. The method showed determination coefficients (r(2)) higher than 0.99, recoveries between 93.2 and 124.3% for spike levels between 0.5 and 2.0 times the maximum residues limit (MRL) values. The repeatability and intermediate precision RSD values ranged from 1 to 19%. Decision limits (CC alpha) and detection capabilities(CC beta)) ranged from 10.7 to 59.4 mu g kg(-1) and 11.4 to 68.8 mu g kg(-1), respectively. Method performance was successfully evaluated by analyzing real samples and proficiency test with a z-score in the range of +/- 1.