Comparison of different sample preparation procedures for multiclass determination of selected veterinary drug, coccidiostat and insecticide residues in eggs by liquid chromatography-tandem mass spectrometry

This paper presents the evaluation of extraction techniques and sample clean-up procedure for the simultaneous determination of residues of veterinary drugs (sulphonamides, fluoroquinolones, tetracyclines, macrolides, β-lactams, nitroimidazoles, benzimidazoles, amphenicols, lincosamides and pleuromutilins), coccidiostats and insecticides in fresh egg samples. The study utilises the liquid chromatography-tandem mass spectrometry technique to obtain suitable analytical parameters for the screening and confirmatory method. The results of egg samples analysed by 8 different sample preparation schemes were compared by using the mean recoveries. The recoveries of analytes showed that both SPE and modified QuEChERS have not been sufficient for the extraction of all the analytes in the expected range of 70–120%. Additional cleaning with dispersive sorbents prolonged the time taken by the sample preparation steps and provided slightly different final extract clarity results. The most demanding analytes to isolate from the samples were coccidiostats, while sulphonamides were the group of analytes for which all the proposed sample clean-up procedures were suitable. As the chosen method, extraction with 0.1% formic acid in acetonitrile–water (8 : 2) and clean-up with HybridSPE can be applied as a sample preparation step for the screening and confirmatory method in official laboratories.