摘要
介绍了用增敏碘量法同时测定微量的Ｍｎ（Ⅱ）、Ｍｎ（Ⅶ）、Ｃｒ（Ⅲ）和Ｃｒ（Ⅵ）。将样品中的Ｍｎ（Ⅶ）和Ｃｒ（Ⅵ）用Ｎａ２ＳＯ３预先还原，在ｐＨ为３．０的醋酸盐介质中对Ｍｎ（Ⅱ）和Ｃｒ（Ⅲ）用过量ＫＩＯ４氧化（当用Ｈ２Ｐ２Ｏ２－７掩蔽Ｃｒ（Ⅲ）时，只有Ｍｎ（Ⅱ）被氧化），过剩的ＩＯ－４用钼酸盐掩蔽，加入ＫＩ后，以Ｎａ２Ｓ２Ｏ３滴定游离出的Ｉ２。此法对Ｍｎ的测定范围为２９～１４７０６μｇ／Ｌ，相对标准偏差为０．３１％～１．１８％；对Ｃｒ的测定范围为５９～１０２９４μｇ／Ｌ，相对标准偏差为０．３６％～１．１２％。此法与常规滴定法测定Ｍｎ和Ｃｒ相比。
An iodometric amplification method has been developed for simultaneous determination of trace amount of Mn(Ⅱ), Mn(Ⅶ), Cr(Ⅲ) and Cr(Ⅵ). Mn(Ⅱ) and Cr(Ⅲ) in the sample are first reduced by Na 2SO 3, then oxidized by excess KIO 4 in acetate medium with pH 3.0[when Cr(Ⅲ) is masked with H 2P 2O 2- 7,only Mn(Ⅱ) is oxidized]. Unreacted IO - 4 is masked with moly bdate. After adding KI, liberated I 2 is titrated with Na 2S 2O 3. The determination range for Mn of this method is 29～14706μg/L with 0.31%～1.18% of relative deviation and that for Cr is 59～10294μg/L with 0.36%～1.12% relative deviation. In comparison with traditional method, this method can offers 20 fold and 12 fold amplification for the determination of Mn and Cr respectively.
出处
《化工环保》
CAS
CSCD
北大核心
1999年第4期233-239,共7页
Environmental Protection of Chemical Industry
