Development of a modified QuEChERS method based on magnetic multiwalled carbon nanotubes for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by UPLC-MS/MS.

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was developed for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Several extraction conditions were tested and optimized, and the obtained extraction efficiency of all the targeted compounds (particularly macrolides) could fulfill the requirements. In the purification procedure, magnetic multiwalled carbon nanotubes (Fe3O4-MWCNTs) were used as adsorbents, and an external magnet was utilized to achieve a faster adsorbent separation, compared to the traditional centrifugation process. The recoveries of all analytes were in the range of 60.5%-114.6% at three fortified levels with relative standard deviations (RSDs) of less than 20%, and the LOQs ranged from 0.1 μg·kg-1 to 17.3 μg·kg-1. This method was successfully applied to the analysis of egg samples, demonstrating its applicability and suitability for the routine analysis of multiclass residues in egg samples.