Study On Extraction Spectrophotometric Determinaion Of Cr(Ⅵ), Ni(Ⅱ) And Zn(Ⅱ) In Aquous Two-Phase System And Its Application

The studies of environmental analysis, especially the analysis of water soluble metal ion in water, are active worldwide from 1980's. Spectrophotometry is the most popular detection method applied to determine water soluble trace metal ion. It is simple and convenient, and its instrument is also simple and low in price. Aqueous two-phase extraction technique, as a new type of separating technique developed from 1950's, has received broad attention in extraction area, because of its advantages, such as, water as solvent, low cost, less volatile, less pollution, fast phase separating speed, simple operation, combination with other techniques. By the integrated application of aqueous two-phase extraction and spectrophotometry, the novel analysis method that aqueous two-phase extraction spectrophotometry was established. It can extract and simultaneously determine metal ions.The spectral properties, composition, color and extraction conditions of chromium (â…¥)-diphenyl hydrazine (DPC) complexes, nickel (â…¡)-dimethyl-glyoxime (DMG) complexes and zinc (â…¡)-zincon complexes in the aqueous two-phase system formed by polyethylene glycol (PEG) 2000 and sodium sulfate were systematically studied, and the novel method of analyzing chromium (â…¥), nickel (â…¡), zinc (â…¡) is established. The selectivity and sensitivity was improved, and the matrix interference was basically eliminated by optimizing the amount of PEG solution, sodium sulfate, chromogenic reagent, the acidity of the system and other factors. The method was evaluated from linear relationship, detection limits, precision, anti-interference capability and so on. The method was applied to analyze industrial waste water, river water, steel and other real samples, and the analytical results were in good agreement with the values measured by atomic absorption spectrometry.