Application of UHPLC-MS/MS method to study occurrence and fate of sulfonamide antibiotics and their transformation products in surface water in highly urbanized areas.

Sulfonamide antibiotics (SAs) are used on a large scale in human and veterinary medicine. The main goal of this study was to develop a method for the detection of selected SAs (sulfamethoxazole, sulfadiazine, sulfamethazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethiazole, and sulfisoxazole) in aqueous samples (targeted analysis), and then conduct a non-targeted analysis to determine the transformation products to elucidate their degradation pathways. These analyses were performed using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The procedure was used to detect selected antibiotics in water samples collected throughout a highly urbanized area. Among the studied compounds, sulfamethoxazole (max. 78.88 ng L-1) and sulfapyridine (max. 38.88 ng L -1) were the most common pollutants identified in surface waters. Trace amounts of sulfadiazine (below LOQ = 0.40 ng L-1) were also detected. Next, the samples were screened to detect the transformation products. Several sulfadiazine and sulfamethoxazole transformation products were detected and confirmed in the environmental samples.