Development and Validation of QuEChERS Extraction Coupled with Ultrahigh-Performance Liquid Chromatography-Tandem...

Veterinary drug residues in aquatic products are often overlooked, yet they pose significant environmental risks and potential threats to human health. In this study, a rapid and sensitive analytical method was developed for the simultaneous determination of nine commonly used macrolide antibiotics in largemouth bass (Micropterus salmoides) muscle using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Sample extraction was performed using 80% acetonitrile in water, followed by purification with Cleanert MAS-Q cartridges. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C₁₈ column (50 mm × 2.1 mm; 1.7 μm), equipped with a Waters VanGuard^TM BEH C₁₈ guard column (1.7 μm), using a mobile phase consisting of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Mass spectrometric detection was conducted in positive electrospray ionization mode (ESI⁺) using multiple reaction monitoring (MRM). The method demonstrated excellent linearity in the concentration range of 0.2-30 ng/mL, with determination coefficients (R²) exceeding 0.9980 for all analytes. Average recoveries ranged from 89.3% to 108.4%, with intraday and interday relative standard deviations (RSDs) of 2.9-11.6% and 4.1-12.5%, respectively. The limits of detection (LOD) and quantification (LOQ) for largemouth bass muscle were determined to be 0.4 μg/kg and 2.0 μg/kg, respectively. The decision limits (CC_α) and detection capabilities (CC_β) ranged from 2.13 to 215.71 μg/kg and 2.22 to 231.42 μg/kg, respectively. The developed method was successfully applied to the quantitative analysis of macrolide residues in 20 largemouth bass samples collected from local markets.