High-density extraction solvent-based solvent de-emulsification dispersive liquid-liquid microextraction combined with MEKC for detection of chlorophenols in water samples.

For the first time, the high-density solvent-based solvent de-emulsification dispersive liquid-liquid microextraction (HSD-DLLME) was developed for the fast, simple, and efficient determination of chlorophenols in water samples followed by field-enhanced sample injection with reverse migrating micelles in CE. The extraction of chlorophenols in the aqueous sample solution was performed in the presence of extraction solvent (chloroform) and dispersive solvent (acetone). A de-emulsification solvent (ACN) was then injected into the aqueous solution to break up the emulsion, the obtained emulsion cleared into two phases quickly. The lower layer (chloroform) was collected and analyzed by field-enhanced sample injection with reverse migrating micelles in CE. Several important parameters influencing the extraction efficiency of HSD-DLLME such as the type and volume of extraction solvent, disperser solvent and de-emulsification solvent, sample pH, extraction time as well as salting-out effects were optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 0.02-4 μg/mL, low LODs (4 ng/mL), and good repeatability of the extractions (RSDs below 9.3%, n = 5). And enrichment factors for three phenols were 684, 797, and 233, respectively. This method was then utilized to analyze two real environmental samples from wastewater and tap water and obtained satisfactory results. The obtained results indicated that the developed method is an excellent alternative for the routine analysis in the environmental field.