Applications Of Cloud Point Extraction In Capillary Electrochromatography

More and more attention was paid by today’s society about environmental and food safety. Naphthols and environmental endocrine-disruptive (EDC) have become common environmental pollutants. Therefore, a simple, fast, low-cost, sensitive and selective monitoring method is usually required. However, the trace determination of naphthols and EDC in the environment is difficult due to their low concentrations and complicated matrix effects. Hence, a pre-concentration technique is necessary, solid-phase extraction(SPE),Solid-phase microextraction (SPME), Dispersive liquid-liquid extraction(DLLE), Dispersive liquid-liquid microextraction (DLLME) and cloud point extraction (CPE). CPE has more advantages include low cost, high efficiency and low toxicity than the other pre-concentration technique. CPE technique has been widely used for extracting trace metals and environmental pollutants coupled with Atomic absorption spectrophotometry (AAS), High performance liquid chromatography(HPLC), gas chromatography(GC) and capillary electrophoresis(CE). A novel dual-cloud point extraction (dCPE) technique was first reported by Yin, it is can eliminate the effect of the surfactant on the detection and separation compared with the traditional cloud point extraction. Therefore, it is become easier coupling with different instruments and expanded its applied range. Although Fluorescence spectrophotometry (FI) more sensitivity than Ultraviolet-visible spectrophotometry(UV),one problem associated with introducing a surfactant-rich phase into FI was that the surfactant would disturbance determination of the object and limit its application. So it is very important to select the appropriate surfactants. Capillary electrochromatogratography (CEC) ic an emerging micro separation technology combines both the robust selectivity of HPLC and merits of high efficiency of CE. In recent years, it is application in the fields of small organic molecule, environment, medicine and biochemical analysis and separation. In this paper, CPE as a pre-concentration technique is set up for extensions and refinements combined with instruments, with the purpose of set up a low cost, fast and high selectivity method to enrich and detect Naphthols and EDC In our living environment.This article is divided into the following three parts work:(1)First, adopts the technical combination of CPE with spectrofluorimetry, thereby realizing the simultaneous determination of1-and2-naphthol. Choose Genapol X-080as surfactant to extract in the cloud point procedure, the effective factors of cloud point including pH, surfactant concentrations, concentration of sodium chloride solution, equilibration temperature and incubation time were optimized. The interferences of similar organic matters were also taken into account. The good linearity was in range from8to32μg·L-1; the relative standard deviation (RSD) of9times determination of1-naphthol and2-naphthol were5.65%and2.65%respectively; the detection limit (CLOD. S/N=3) of1-naphthol and2-naphthol were0.07μg·L-1and0.05μg·L-1respectively; This method can be successfully applied to the measurement of1-naphthol and2-naphthol in river water sample.(2) Dual-cloud point extraction coupled with Capillary electrochromatography with ultraviolet detector applied to the determination of naphthols. Triton X-114was used as surfactant. The naphthols were extracted into aqueous phase under acid condition,0.1M NaOH solution was used to pH-mediated and the analytes was transferred into aqueous phase. During the second heating and centrifugation, most of the surfactant separate from the analytes. Not only the better concentration effect obtained, but also effectively avoids the interference of surfactant. The pH value, bath temperature, bath time, the quantity of NaOH and similar organic interference were investigated and optimized. The appropriate pH-mediated dual-cloud point extraction method was established. The wastewater of two factory was treated by pH-mediated dual-cloud point extraction and and then detected by spectrofluorimetric at λex/λem=308nm/360nm and λex/λem=328nm/360nm., the concentration of1-naphthol and2-naphthol is16.2μg·L-1and12.8μg·L-1respectively. The recovery show that the satisfactory between91.2%and98.0%. (3) Dual-cloud point extraction coupled with Capillary electrochromatography was with fluorescence detector (270nm exciting wavelength and310nm emitting wavelength) applied to the determination of bisphenols endocrine-disruptive for the first time. In dCPE, during a single sample pretreatment twice process cloud point extraction procedure is carried out, bisphenols are back extracted into the aqueous phase at the second procedure, and thus the effect of the surfactant on the capillary-column chromatography is eliminated in the process of separation. The factors affecting pH-mediated dCPE and CEC separation process were investigated and optimized. Five bisphenols were extracted successfully and analyzed directly without the surfactant fluorescence interference. Under the optimum conditions, the enhancement factor (calculated as the ratio of the volume of preconcentrating samples to the volume of the back-extraction alkaline aqueous phase) was about33.33-fold and base-line separation for five bisphenols achieved within15min. To evaluate the quantitative applicability of the method, the calibration curves was established based on the linear relationships between the peak area and the analyte concentration was tested and showed good linearity(R20.9904～0.9971). The proposed method was applied to baby’s bottle detection and found the concentrations of Bisphenols A about12.0μg·L-1.The proposed methods were shown to be a green, rapid and effective approach for preconcentration and determination of trace bisphenols present in actual samples.