(長沙工業(yè)高等專科學(xué)校冶金系，長沙 410012；
中南工業(yè)大學(xué)化學(xué)系， 長沙 410083)
摘 要: 介紹了測(cè)定微克量級(jí)Mn(Ⅱ)和 Cr(Ⅲ)的簡單、 快速、 高增敏碘量法。在pH=3.0的醋酸鹽介質(zhì)中， 沒有焦磷酸鈉存在時(shí)，Mn(Ⅱ)和Cr(Ⅲ)同時(shí)被過量加入的高碘酸根氧化， 而有焦磷酸鈉存在時(shí)， 只有M n(Ⅱ)被氧化；過剩高碘酸根用鉬酸根掩蔽后， 加入碘化鉀， 滴定游離出的單質(zhì)碘。 Mn( Ⅶ)和Cr(Ⅵ)混合物及Mn(Ⅱ)，Mn(Ⅶ)，Cr(Ⅲ) 和Cr(Ⅵ)混合物， 可以用亞硫酸鈉還原后再以本法測(cè)定。 相對(duì)于常規(guī)滴定，本法分別對(duì)錳和鉻增敏20和12倍。 此法成功地測(cè)定了幾種樣品。
關(guān)鍵字: 增敏碘量法 掩蔽 連測(cè) 錳 鉻
（Department of Metallurgy, Changsha Technical College, Changsha 410012, P. R. China
Department of Chemistry, Central South University of Technology, Changsha 410083, P. R. China）
Abstract:A simple, rapid and highly sensitive iodometric amplification method was developed for the determination of microgram a mount of Mn(Ⅱ) and Cr(Ⅲ). The method is based on both oxidations of Mn(Ⅱ) as well as Cr(Ⅲ) in the absense of sodium pyrophosphate and only oxidation of Mn(Ⅱ) in the presence of sodium pyrophosphate with excess of periodate in acetate buffer(pH=3.0), removal of unre acted periodate by masking with molybdate, and subsequent titration of the liberated iodine after adding iodide.The developed method was found suitable for the analysis of the mixture of Mn(Ⅶ)and Cr(Ⅵ) and the elemental analyses of Mn and Cr in the mixture of Mn(Ⅱ), Mn(Ⅶ), Cr(Ⅲ) and Cr(Ⅵ) after the reduction with sodium sulphite, too. Various samples have been successfully analysed by this method with 20 times and 12 times amplification for Mn and Cr, respectively.
Key words: iodometric amplification simultaneous determination masking Mn Cr
