Key Takeaways & Executive Findings
- •• • The combined SPE-GPC cleanup reduced matrix suppression, achieving LODs of 0.7–4.4 ng·L−1 and LOQs of 2.8–17.6 ng·L−1, enabling trace-level detection in complex water matrices. • • Recoveries at three spiking levels (10, 200, 400 ng·L−1) ranged from 44.5%–115%, with RSDs below 10% across all levels, demonstrating accuracy and precision suitable for regulatory monitoring. • • The method detected five sulfonamides in real samples at concentrations up to 3864 ng·L−1, confirming its applicability to surface water and wastewater effluent analysis. • • The use of Na2EDTA (2.5 mg·L−1) and pH adjustment to 6 were critical for chelating metal ions and optimizing extraction efficiency, addressing common pitfalls in antibiotic analysis.
Abstract
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.
1. Introduction
Environmental water samples, particularly wastewater, present severe matrix suppression effects that compromise the accuracy of sulfonamide antibiotic quantification. Conventional solid-phase extraction alone often fails to eliminate co-extracted interferences, leading to ion suppression or enhancement in mass spectrometry and unreliable results. This bottleneck has hindered reliable risk assessment and regulatory compliance monitoring of antibiotic residues in aquatic environments.
The present study addresses this challenge by integrating gel permeation chromatography (GPC) as a secondary cleanup step after SPE. This dual-stage purification effectively removes high-molecular-weight matrix components, as evidenced by improved recoveries (44.5%–115%) and low RSDs (≤10%) across spiking levels. The method achieves sub-ng/L detection limits (0.7–4.4 ng·L−1), making it a robust and cost-effective solution for routine surveillance of sulfonamides in complex environmental matrices.
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FAN Pei, ZHANG Huiqiang, DONG Hengtao, ZHANG Qinming, ZHANG Chun, WANG Fei, FAN Zhichao, LI Qi (2026). 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. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2024121201
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Frequently Asked Questions
What is the primary advantage of incorporating gel permeation chromatography (GPC) after solid-phase extraction (SPE) in terms of matrix effect reduction?
GPC acts as a secondary cleanup that removes high-molecular-weight interferences (e.g., humic acids, proteins) co-extracted during SPE. This reduces ion suppression in the electrospray source, as reflected by improved recoveries (44.5%–115%) and low RSDs (≤10%) across spiking levels, compared to SPE-only methods that often suffer from severe matrix effects.
How does the method perform in terms of sensitivity and quantification limits for trace-level monitoring?
The method achieves LODs of 0.7–4.4 ng·L−1 and LOQs of 2.8–17.6 ng·L−1, which are sufficiently low to detect sulfonamides at environmentally relevant concentrations. For instance, in real samples, five sulfonamides were quantified at concentrations ranging from 1.82 to 3864 ng·L−1, demonstrating its capability for trace-level surveillance.
What are the critical sample preparation parameters that influence extraction efficiency?
Key parameters include filtering through 0.45 μm membranes, adjusting pH to 6, and adding Na2EDTA at 2.5 mg·L−1. The pH adjustment ensures optimal ionization of sulfonamides for retention on the Oasis HLB sorbent, while Na2EDTA chelates divalent metal ions that could otherwise complex with analytes or interfere with extraction, thereby enhancing recovery.
How does the method's precision and accuracy compare to existing analytical protocols for sulfonamides?
The method demonstrates excellent precision with RSDs ranging from 0.64% to 10% across three spiking levels (10, 200, 400 ng·L−1). Recoveries between 44.5% and 115% are within acceptable ranges for trace analysis, and the use of internal standards further corrects for variability. These metrics are comparable or superior to many published methods, especially in complex wastewater matrices.
What is the practical applicability of this method for routine monitoring in environmental laboratories?
The method is operationally simple and cost-effective, requiring standard laboratory equipment (SPE, GPC, UPLC-MS/MS). It has been successfully applied to surface water and wastewater treatment plant effluents, detecting five sulfonamides at concentrations up to 3864 ng·L−1. Its robustness and high throughput make it suitable for large-scale monitoring programs aimed at assessing antibiotic contamination and mitigating environmental risks.
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