Abstract:

An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of bromophenols in water samples. The extraction parameters such as extraction solvent, extraction time, ionic liquid single-drop volume, ionic strength and organic solvent were systematically investigated. For the SDME of the three bromophenols, a [C₄MIM]PF₆] microdrop was exposed for 8 min to the aqueous sample with 10% (w/w) NaCl and then was directly injected into a capillary column for analysis. Under the optimal conditions, good linear relationships were obtained in the concentration range of 1-100 mg/L with the correlation coefficients of 0.9939-0.9988 for the bromophenols. The detection limits of the three bromophenols were 0.3 mg/L. The RSDs of peak areas of the standards were 5.21%-6.47% (n=6). And the enrichment factors for the three bromophenols were 115.8, 327.0 and 569.8. The proposed method was applied to the determination of the three bromophenols in tap, river and lake waters with the recoveries of the three bromophenols in the range of 87.8%-96.7%. The method is suitable for the quantification of bromophenols in water samples.

Key words: bromophenols, capillary electrophoresis (CE), ionic liquid, on-line coupling, single-drop microextraction, water