Hexafluoroisopropanol-mediated cloud point extraction of organic pollutants in water with analysis by high-performance liquid chromatography.

Abstract

A hexafluoroisopropanol (HFIP)-mediated cloud point extraction (CPE) system was established. A small amount of HFIP (even 1%, v/v) can dramatically reduce the cloud point of Triton X-100 (TX-100) aqueous solution (even to 1°C) and make liquid-liquid two-phase separation (coacervate phase and aqueous phase) occur at room temperature over a wide range of TX-100 concentration (0.5∼10%, g/mL). HFIP-mediated coacervate phase has smaller volume (volume ratio is 1.8∼8.9% relative to the volume of the total solution with 1∼5% TX-100) and larger micelle aggregates (30∼80nm in diameter) compared to temperature-induced coacervate phase (volume ratio at 2.8∼14.0%, the diameter of micelle aggregates at 5∼30nm). HFIP-mediated CPE was coupled to high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for the extraction and detection of organic pollutants in water, namely, polycyclic aromatic hydrocarbons (PAHs), fluoroquinolones (FQs), and sulfonamides (SAs) with different polarities, charges, and hydrogen-bonding properties. HFIP-mediated CPE provides much higher extraction rates (ERs) and enrichment factors (EFs) for FQs (91∼106%, 50∼59), PAHs (63∼90%, 33∼49), and SAs (26∼55%, 16∼34) compared with the temperature-induced one (ERs: 4∼8% for FQs, 25∼46% for PAHs, and 4∼37% for SAs; EFs:1∼3 for FQs, 6∼12 for PAHs, and 8∼13 for SAs). The limit of detection ranges from 0.24 to 0.33ng/mL for FQs, 0.04 to 0.38ng/mL for PAHs, and 0.63 to 1.31ng/mL for SAs. The proposed method was applied in the analysis of real water samples, and the recovery of 79.4∼110.8% and the relative standard deviation of 0.2∼16.3% were achieved for the three types of pollutants. Graphical abstract Schematic illustration of HFIP-mediated cloud point extraction.