Development and testing of a method for determining sulfonamides in water using liquid chromatography-mass spectrometry

   Introduction: The presence and spread of antibiotics and antimicrobials in the natural environment is a serious concern worldwide.

   Objective: To develop and test a method for determining sulfonamides in water using high-performance liquid chromatography with mass-spectrometric detection (HPLC/MS-MS).

   Materials and Methods: The study involved samples of various types of water (drinking water, surface and groundwater, swimming pool water, treated wastewater, etc.) collected in 2024–2025 in an industrial city. Over 150 samples of various water types were analyzed during the development, establishment of metrological characteristics, and testing of the methodology. Laboratory testing was carried out using high-performance liquid chromatography with mass spectrometric detection. Conditions for the effective extraction of sulfonamides from water were established using solid-phase extraction with Oasis HLB cartridges.

   Results: We developed a selective and highly sensitive method for determining sulfonamides in water using high-performance liquid chromatography–mass spectrometry in the concentration range from 3 to 4,000 ng/dm³ with a determination error of 46–50 %. Conditions for the efficient extraction of sulfonamides from water using solid-phase extraction in Oasis HLB cartridges and a 0.2 % solution of formic acid in acetonitrile as an eluent have been elaborated. The average extraction rate of sulfonamides from various types of water ranged from 75 % to 100 %. As a result of testing the method for determining sulfonamides in various types of water samples, the qualitative presence of six out of seven determined compounds was established in 75 % of the samples, of which sulfanilamide, sulfathiazole, and sulfadimethoxine were detected above the lower limit of detection in the concentration range from 4 to 110 ng/dm³. No exceedances were detected.

   Conclusion: The study results confirm the feasibility of using high-performance liquid chromatography combined with solid-phase extraction for testing sulfonamides in water at levels representative of their actual concentrations in aqueous matrices.

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