In situ derivatization and hollow-fiber liquid-phase microextraction to determine sulfonamides in water using UHPLC with fluorescence detection.

A sensitive method for determining sulfonamides in water was developed and validated through in situ derivatization and hollow-fiber liquid-phase microextraction with ultra-high performance liquid chromatography and fluorescence detection. The target sulfonamides were sulfadiazine, sulfacetamide, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole, and sulfisoxazole. Following in situ derivatization with fluorescamine, three-phase hollow-fiber liquid-phase microextraction with an S 6/2 polypropylene hollow-fiber membrane was applied automatically using a multipurpose autosampler. Experimental parameters including derivatization time, choice of organic phase, pH of donor and acceptor phase, stirring rate, extraction temperature and time were optimized. Under optimized conditions, the target sulfonamides achieved excellent linearity with correlation coefficients of 0.9924-0.9994 within the concentration range of 0.05-5 μg/L. The limits of detection of the eight sulfonamides were 3.1-11.2 ng/L, and the limits of quantification were 10.3-37.3 ng/L. Enrichment factors of 0.1 and 5 μg/L sulfonamides spiked in lake water were 14-60, and recoveries were 56-113% with relative standard derivations of 3-19%. Applied with the developed method, sulfamerazine and sulfamethoxazole were measurable in both influent and effluent water of the three sewage treatment plants in Guangzhou, China. The developed method was sensitive and provided an alternative method for simultaneously enriching and quantifying multiple sulfonamides in environmental water.