Determination of 11 Sulfonamide Antibacterial Drug Residues in Syngnathus by Ultra-Performance Liquid Chromatography-Mass Spectrometry Combined with Dispersed Solid Phase Extraction

An analytical method for the determination of 11 sulfonamide antibacterial drug residues in Syngnathus by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) has been established. The samples were extracted by ultrasonication with 2% formic acid-acetonitrile, purified by an enhanced matrix removal lipid-dispersed solid phase extraction (EMR-Lipid dSPE), and separated on a Waters ACQUITY BEH C₁₈ column (1.7 μm, 2.1 mm×100 mm). The analytes were detected by mass spectrometry using the positive electrospray ionization mode under multiple reaction monitoring mode (MRM), with 2 mmol/L ammonium acetate-0.1% formic acid in aqueous solution and 0.1% formic acid in acetonitrile as mobile phases by a gradient elution program, and quantified by the external standard method. The results showed that the 11 antibacterial sulfonamides had good linearity in the range of 0~30 ng/mL, the correlation coefficient (R²) were all greater than 0.9959, the limit of detection (LOD) and quantitation (LOQ) were in the range of 0.11~1.30 µg/kg and 0.37~4.40 µg/kg, respectively. At three spiked levels of 20.0, 50.0 and 100.0 µg/kg, the spiked average recoveries of the analytes were in the range of 62.5%~118.1%, and the relative standard deviation was 2.1%~9.2%. The method is accurate, straightforward, and is suitable for the rapid screening of 11 sulfonamide antibacterial drug residues in Syngnathus.