Hexafluoroisopropanol-induced coacervation in aqueous mixed systems of cationic and anionic surfactants for the extraction of sulfonamides in water samples

Hexafluoroisopropanol (HFIP)-induced coacervation in aqueous mixed systems of catanionic surfactants of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) was described in detail, and its application in the extraction of strongly polar sulfonamides (SAs) was investigated. With 10 % (v/v) HFIP inclusion, coacervation formation and two-phase separation occur in a wide range of SDS/DTAB mole ratios (88:12 similar to 0:100 mol/mol) and total surfactant concentrations (10 similar to 200 mmol/L). The interactions between HFIP and DTAB play an important role in coacervation formation. The HFIP-induced SDS-DTAB coacervation extraction proves to be an efficient method for the extraction and preconcentration of SAs. Both hydrophobic interaction and polar interactions (hydrogen-bond, electrostatic, and pi-cation) contribute to the distribution of SAs into coacervate phase. The proposed HFIP-induced SDS-DTAB coacervation extraction combined with HPLC-UV was employed for the extraction and quantitative determination of SAs in environmental water samples. Limits of detection were 1.4 similar to 2.5 ng mL(-1). Excellent linearity with correlation coefficients from 0.9990 to 0.9995 was obtained in the concentration of 0.01 similar to 10 mu g mL(-1). Relative recoveries were in the range of 93.4 similar to 105.9 % for analysis of the lake, underground, and tap water samples spiked with SAs at 0.01, 1.0, and 10 mu g/mL, respectively. Relative standard deviations were 0.7 similar to 3.2 % for intraday precision and 1.3 similar to 4.6 % for interday precision (n = 3). Concentration factors were 17 similar to 49 for three water samples spiked with 0.01 mu g/mL SAs. The results demonstrate that the proposed extraction method is feasible for the preconcentration and determination of trace SAs in real water samples.