β修正分光光度法测定微量铬

采用β修正分光光度法测定铬（Ⅵ）含量，缓冲溶液ｐＨ５─６，显色剂为苯芴酮（ＰＦ），阳离子表面活性剂ＣＴＭＡＢ对该反应体系有增溶增敏作用，用β修正分析理论研究微量铬（Ⅵ）及其与ＰＦ络合比测定。结果表明，Ｃｒ（Ⅵ）－ＰＦ络合比为ｌ：３较好，铬在０─１０．０μｇ／２５ｍｌ范围，修正吸光度Ａ＿ｃ遵循焦耳定律；铬最低检测浓度为０．０２ｍｇ／ｌ，相对标准偏差ＲＳＤ≤４．３％，铬加标回收率９１．８％─１０９％。该法可消除显色体系中过量显色剂干扰，修正计算络合产物真实吸光度，提高分析精密度及准确度，适合于工业废水铬分析测定。

Use of βCorrection Spectrophotometry for the Determination of Trace Chromium

correction spectrophotometry is a new analytical method that is different from otherdual-wavelength methods.βcorrection absorbance can eliminate completely the interferenceof excess colorant to get real absorbance of the produced complex. With the help of thisprinciple the complex-ratio can be determined accurately.In pH5─6 buffer solution Chromi-um(Ⅵ)can react with phenylfluorone(PF)to form a red complex. The cationic surfac-tant, CTMAB is used for increasing analytical sensitivity and for dissolving PF and itschromium complex. Based on this colored reaction,βcorrection spectrophotometric methodis studied for the determination of trace amounts of chromium in wastewater and calculationof the complex-ratio of Cr(Ⅵ)-pF. Experimental results show that precision, accuracy andsensitivity have been improved,and the complex-ratio of Cr-pF equals 1/3. Beer′s law isobeyed over the concentration of 0-10.0μg/25ml of chromium(Ⅵ). The detection limit ofchromium is 0. 02mg/l,relative standard deviation less than 4.3%,and recovery between91.8%-109%。The method is suitable for the determination of industrial wastewater.