Dual-cloud point extraction coupled to high performance liquid chromatography for simultaneous determination of trace sulfonamide antimicrobials in urine and water samples

Dual-cloud point extraction (dCPE) was successfully developed for simultaneous extraction of trace sulfonamides (SAs) including sulfamerazine (SMZ), sulfadoxin (SDX), sulfathiazole (STZ) in urine and water samples. Several parameters affecting the extraction were optimized, such as sample pH, concentration of Triton X-114, extraction temperature and time, centrifugation rate and time, back-extraction solution pH, back-extraction temperature and time, back-extraction centrifugation rate and time. High performance liquid chromatography (HPLC) was applied for the SAs analysis. Under the optimum extraction and detection conditions, successful separation of the SAs was achieved within 9 min, and excellent analytical performances were attained. Good linear relationships (R2 ≥ 0.9990) between peak area and concentration for SMZ and STZ were optimized from 0.02 to 10 μg/mL, for SDX from 0.01 to 10 μg/mL. Detection limits of 3.0-6.2 ng/mL were achieved. Satisfactory recoveries ranging from 85 to 108% were determined with urine, lake and tap water spiked at 0.2, 0.5 and 1 μg/mL, respectively, with relative standard deviations (RSDs, n = 6) of 1.5-7.7%. This method was demonstrated to be convenient, rapid, cost-effective and environmentally benign, and could be used as an alternative tool to existing methods for analysing trace residues of SAs in urine and water samples.