用水解分离-原子吸收光谱法对锰作形态分析

研究了痕量锰形态分析的水解分离-原子吸收光谱法.依据不同价态锰水解酸度的不同,使以各种形态存在的锰彼此分离以对其进行AAS测定.用NaOH溶液调试样的pH到10,此时以MnO-4形式存在的高价锰不产生水解沉淀,而低价Mn(Ⅱ)和中价Mn(Ⅳ)产生水解沉淀,对清液中的Mn(Ⅶ)进行AAS测定;然后用pH为5的硫酸溶液溶解沉淀,此条件下Mn(Ⅱ)的沉淀溶解,从而使Mn(Ⅱ)和Mn(Ⅳ)彼此分离,对清液中的Mn(Ⅱ)进行AAS测定;最后,用pH为1的硫酸溶液溶解Mn(Ⅳ),并沉淀进行AAS测定.从上述测定,可分别求得Mn(Ⅱ),Mn(Ⅳ)和Mn(Ⅶ)含量.该方法的加标回收率分别在93.3%～99.5%,96.7%～103%和98.2%～104%之间,相对标准偏差分别为2.7%,3.2%和3.1%,检出限为0.10mg·L-1,该法简单,快速,准确.

Speciation Analysis of Manganese in Water Sample Using Flame Atomic Absorption Spectrometry with Hydrolysis Separation System

A rapid and sensitive method for the sequential determination of Mn(II), Mn (lV) and Mn( VII) in water samples based on flame atomic absorption spectrometry with hydrolysis separation system has been developed. In the proper acidity, the manganese in different kind of speciation was separated by using hydrolysis acidity. The pH of sample containing manganese in different kind of speciation was adjusted to 10 by using NaOH solution, and at pH 10 of the medium, Mn( II) and M(IV) were precipitated as hydrolysis precipitation, while Mn(VII) remaining in the solution was determined by AAS. After that, hydrolysis precipitation of Mn( II) was solvated by adding sulfuric acid with pH 5 as solvent and determined by AAS. Finally, hydrolysis precipitation of Mn(IV) was solvated by adding sulfuric acid with pH 1 as solvent and determined by AAS. The recoveries are 93. 3%-99. 5% for Mn( II), 96. 7%-103% for Mn(IV) and 98. 2%-104% for Mn(VII), the relative standard deviations are 2. 7%, 3. 2% and 3. 1% respectively, and the detection limits are 0. 10 mg x L(-1).