Determination of 19 Sulfonamide Antibiotics in Suface Water and Waste Water by Ultra Hight Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry

The water samples were collected in brown high-density polyethylene bottles or glass bottles and pretreated as soon as possible, and stored at 4℃ for no more than 7 days. The collected sample was filtered through a 0.45 μm filter and 1 g of Na₂EDTA was added into 1 L of the sample. The pH of the sample solution was adjusted to 6.0 with 0.1 mol·L^-1 NaOH solution, and the OASIS HLB solid phase extraction column was used for enrichment and extraction of the analytes. After the column was washed with 10 mL of water and dried in vacuum for 10 min, the analytes was eluted with 10 mL of methanol and the eluate was collected and concentrated by nitrogen-blowing to dryness. The residue was diluted to 1 mL with the initial mobile phase, and 50 μL of 1.00 mg·L^-1 mixed internal standard solution was added, then the solution was filtred with 0.20 μm hydrophilic polypropylene membrane. The analytes were seperated on a HYPERSIL GOLD C₁₈ column (100 mm×2.1 mm, 1.9 μm), with 0.05% (volume fraction) formic acid solution and methanol as the mobile phase for gradient elution. Electrospray positive ion source and multiple reaction monitoring mode were used in mass spectrometry analysis. Linearity range of 19 sulfonamide antibiotics was same 2.0-100 μg·L^-1, with detection limits (3.143s) in the range of 0.6-2.0 ng·L^-1. Values of recovery obtained by standard addition method ranged from 77.6% to 134%, and RSDs (n=6) ranged from 1.9% to 11%. The method was applied to the determination of antibiotic residues in the surface water and wastewater from a farming enterprise, only two targets with mass concentrations of 2.60, 2.10 ng·L^-1 were found in the surface water, and 7 targets with mass concentrations in the range of 2.82-34.3 ng·L^-1 were found in the wastewater from a farming enterprise.