Wei Wei, Yin Xue-Bo, He Xi-Wen
Research Center for Analytical Sciences and Department of Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
J Chromatogr A. 2008 Aug 22;1202(2):212-5. doi: 10.1016/j.chroma.2008.07.015. Epub 2008 Jul 11.
pH-mediated dual-cloud point extraction (dCPE) technique for capillary electrophoresis (CE) determination of phenol and m-nitrophenol is proposed in this paper. This technique for the preconcentration and clean-up of the two analytes includes two steps through simple pH-mediation. The analytes are transferred into surfactant-rich phase in the first step (under acidic condition) with Triton X-114 as the extractant because the two analytes become hydrophobic in acidic solution. They were back-extracted into alkaline aqueous phase in the second cloud point step. Because the concentration of Triton X-114 in the final aqueous solution after dCPE is only around critical micelle concentration, its adsorption on the inner wall of capillary and its possible influence on electrophoretic separation are eliminated. Baseline separation of phenol and m-nitrophenol is realized in a 60 cm x 75 microm i.d. capillary at 18 kV using 50 mM boric acid solution (pH 9.5). The preconcentration factors are 24.0 for phenol and 22.5 for m-nitrophenol. The detection limits of phenol and m-nitrophenol are 2.0 x 10(-6) mol L(-1) and 2.5 x 10(-6) mol L(-1), respectively. The proposed method was successfully applied to the determination of two analytes in spiked natural water samples.
本文提出了一种用于毛细管电泳（CE）测定苯酚和间硝基苯酚的pH介导双浊点萃取（dCPE）技术。该技术用于两种分析物的预富集和净化，通过简单的pH调节包括两个步骤。第一步（在酸性条件下），以Triton X-114作为萃取剂，将分析物转移到富含表面活性剂的相中，因为这两种分析物在酸性溶液中变得疏水。在第二个浊点步骤中，它们被反萃取到碱性水相中。由于dCPE后最终水溶液中Triton X-114的浓度仅约为临界胶束浓度，消除了其在毛细管内壁上的吸附及其对电泳分离的可能影响。使用50 mM硼酸溶液（pH 9.5），在60 cm×75 μm内径的毛细管中于18 kV下实现了苯酚和间硝基苯酚的基线分离。苯酚的预富集因子为24.0，间硝基苯酚的预富集因子为22.5。苯酚和间硝基苯酚的检测限分别为2.0×10⁻⁶ mol L⁻¹和2.5×10⁻⁶ mol L⁻¹。所提出的方法成功应用于加标天然水样中两种分析物的测定。
