双波长等吸收点法同时测定水样中Cr(Ⅲ)和Cr(Ⅵ)的含量

Simultaneous Determination of Cr(Ⅲ) and Cr(Ⅵ) by Using Dual-wavelength Isobestic Point Spectrophotometry

采用双波长分光光度法中的等吸收点法对水中Cr(Ⅲ)和Cr(Ⅵ)进行了同时测定。Cr(Ⅵ)的测定波长为351 nm,参比波长为441 nm,Cr(Ⅲ)在572 nm处直接测定。用该方法对Cr(Ⅲ)和Cr(Ⅵ)分别建立标准曲线,相关系数分别为0.997 5和0.997 8。对6组浓度、比例各不相同的Cr(Ⅲ)和Cr(Ⅵ)混合溶液样品进行测定,平均回收率分别为99.60%和99.61%。结果表明,本方法可用于Cr(Ⅲ)和Cr(Ⅵ)的同时测定。

The determination methods of Cr（III） and Cr（VI） can be broadly divided into two categories： determination after separation and simultaneous determination. In this study, the contents of Cr （III） and Cr（VI） in water samples were determined simultaneously by using the dual wavelength absorption method. For Cr（ VI）, the detection wavelength was 351 nm with the reference wavelength of 441 nm, while the Cr（III） was determined at 572 nm directly. The correlation coefficients （R2） of the standard curves for Cr （III） and Cr （VI） were 0. 9975 and 0. 9978 respectively. The concentrations of- Cr（III） and Cr（VI） in 6 different mixtures were determined with the method. As a result, the average recoveries reached to 99.60% and 99.61%, respectively. The results show that the method can be used for simultaneous determination of content of Cr（III） and Cr（VI） in water samples.