Determination of Sulfonamide Antibiotics in Environmental Aqueous Samples by Solid-Phase Extraction–Gel Permeation Chromatography Purification Coupled with Ultra-Performance Liquid Chromatography–Triple Quadrupole Mass Spectrometry
A method for the simultaneous determination of 19 sulfonamide antibiotics in environmental aqueous samples was developed by integrating solid-phase extraction (SPE) and gel permeation chromatography (GPC) with ultra-performance liquid chromatography–triple quadrupole mass spectrometry (UPLC-MS/MS). Aqueous samples were filtered through 0.45 μm membranes, adjusted to pH 6, and treated with Na2EDTA at 2.5 mg·L−1 to mitigate matrix effects. Analytes were enriched on Oasis HLB cartridges, purified by GPC, and separated on a Hypersil GOLD C18 column (2.1 mm ID × 100 mm, 1.9 μm) using gradient elution with 0.05% (V/V) formic acid in water and methanol. Detection was performed in multiple reaction monitoring (MRM) mode with internal standard quantification. Under optimal conditions, limits of detection (LOD) and quantification (LOQ) ranged from 0.7–4.4 ng·L−1 and 2.8–17.6 ng·L−1, respectively. Recoveries from spiked real samples at 10, 200, and 400 ng·L−1 were 44.5%–102%, 47.7%–97.5%, and 51.4%–115%, with relative standard deviations (RSDs) of 1.8%–10%, 0.64%–5.9%, and 0.71%–4.6%, respectively. The method was applied to three surface waters and three municipal wastewater treatment plant effluents, detecting five sulfonamides at concentrations ranging from 1.82 to 3864 ng·L−1. The combined SPE-GPC cleanup effectively reduced matrix suppression, offering high sensitivity, precision, and robustness for routine monitoring of sulfonamide antibiotics in environmental waters.