变色酸单偶氮化合物吸光光度法测定痕量铬(Ⅲ)

SPECTROPHOTOMETRIC DETERMINATION OFTRACE CHROMIUM(III) WITH SOME MONOAZOCOMPOUNDS OF CHROMOTROPIC ACID

本文报道了利用一些变色酸单偶氮化合物测定铬(Ⅲ)的分析方法.在醋酸一醋酸钠缓冲介质中.变色酸2C、铬蓝SE、酸性铬深蓝、铬偶氮酚KS、酸性铬蓝K与铬(Ⅲ)在加热的条件下生成稳定的有色鳌合物,摩尔吸光系数最高可达 2.24×10~4 L·mo1^(-1)·cm^(-1).以铬(Ⅲ)-铬蓝SE体系为例,测定了鳌合物的组成,研究了干扰离子的影响及消除方法,用氢氧化铍共沉淀法分离富集了水中的铬(Ⅲ),使方法具有良好的选择性和很高的灵敏度,用于天然水、废水和合成水样中痕量的铬(Ⅲ)的测定,获得了满意的结果.

A selective and sensitive method for spcctrophotometric determination of chromium (Ⅲ) with some monoazo compounds of chromotropic acid in aqueous solution is proposed. In the weak acid medium of acetate buffer, chromium(Ⅲ) reacted with chromotrope 2C, Eriochrome blue SE, Chromoazol KS, Acid chrome dark blue and Acid chronic blue K upon heating in the boiling water bath to form the colour full chelate compounds, the maximum molar absorptivity is 2.24 × 104L . mol-1.cm-1. Taking Chromium(Ⅲ)-Eriochrome blue SE for an example, the composition of the chelate compound is investigated, the authors studied the effect of interfering ions and elimination, concentrated and separated the chromium(Ⅲ) in water by beryllium hydroxide co-procipitation, and this method is of very good selectivity as well as sensitivity. When it is used for the spcctrophotometric determination of traces chromium(Ⅲ) in natural water, industral waste water and synthetic water samples, satisfactory results arc obtained.