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

Abstract

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.

Vortex-assisted low density solvent liquid–liquid microextraction and salt-induced demulsification coupled to high performance liquid chromatography for the determination of five organophosphorus pesticide residues in fruits

“…This approach still suffers from the decreased partition coefficients of analytes into the extraction solvent [15,[22][23][24].…”

“…Recently, demulsified DLLME has been introduced with its advantages of simplicity and fast extraction [15,[22][23][24]. In demulsified DLLME, the demulsifier is added to facilitate the phase separation of the aqueous phase and the organic extraction phase, thus the centrifugation step is omitted.…”

Salt De-Emulsification Dispersive Liquid-Liquid Microextraction and Back-Extraction Combined with Sweeping Micellar Electrokinetic Capillary Chromatography for Detection of Triazine Herbicides in Honey

“…Hence, to improve the CE sensitivity, various off-line or on-line methods have been developed prior to CE separation (Wang et al 2006;Cheng et al 2014). Despite DLLME successful combination with many atomic and chromatographic techniques, there are still very few reports on the application of DLLME prior to CE (Herrera-Herrera et al 2010;Wen et al 2011;Liang et al 2013;Zhang et al 2012;Xue et al 2013). The combination of DLLME with CE poses some technical challenges, because the organic extractants, which are immiscible with water, are not injectable in conventional aqueous CE.…”

Dispersive liquid–liquid microextraction of five chlorophenols in water samples followed by determination using capillary electrophoresis

“…HPLC‐UV has the disadvantages of consuming organic solvents and lower detection sensitivity. CE is an ideal alternative with high resolution, short analysis time, low solvent consumption, and flexible separation modes . However, CE‐UV often faces a severe problem of poor sensitivity for use at trace and ultratrace analysis owing to small injection volume and narrow optical path length .…”