溴氧化甲基红褪色光度法测定大气中游离溴

Determination of free bromine in air by decoloration oxidation action of methyl red with free bromine

利用溴(Br2)能氧化甲基红溶液并使其褪色,褪色程度与溴量呈线性关系的原理,通过对溶液酸度、各试剂用量等反应条件和可能存在的干扰进行了研究,建立了一种测定大气中游离溴的分析方法.方法的检出限为0.25μg/10ml,摩尔消光系数ε=3.9×104,线性范围为0～16μg/10ml.分别测定含溴量为2.4μg和5.60μg,结果表明,相对标准偏差在6.7%和5.0%(n=9)之间,相对误差小于7.0%.

Methyl red can be oxidized and decolorised by free bromine in acid solution,and the amount of free bromine is liner to the decoloration degree.Based on the principle a method of determination of free bromine in air was established. Such optimum conditions were studied as the selections of amounts of potassium bromide,methyl red and sulfuric acid. The possible interferences also were studied too,and it was found that chlorine,sulfuric dioxide,sulfuric hydrogen and arsenic(Ⅲ)may interfere with the analysis to a different degree,but most metals ions,which possibly were adsorbed on or contained in suspended particles,were allowed to coexist in analysis solution. The detection limit was 0.25μg/10ml,molar absorptivity was 3.9×10~4,and the linearity range was 0～16μg/10ml. Determination of two samples, in which the amounts of free bromine were 2.24μg and 5.60μg respectively,showed that the relative standard deviations ranged from 6.7% to 5.0%(n=9) with no more than 7.0% of relative errors.