以溴化钾-溴酸钾-2′,7′-二氯荧光素为试剂对痕量水杨酸的间接荧光测定法

Fluorimetric Method for the Determination of Trace Salicylic Acid with KBrO_3-KBr and 2′,7′-Dichlorofluorescein

在pH为3.8～7.0范围内，利用Br2（0.5 mol/L H2SO4介质中，Br－与BrO-３反应生成）与2′,7′－二氯荧光素反应，使2′,7－二氯荧光素荧光猝灭。当加入水杨酸时，水杨酸的溴代反应使体系荧光增强，建立了荧光法间接测定痕量水杨酸的新方法。该体系激发波长，发射波长分别为雃x505nm, ?em520nm。水杨酸浓度在2.0～48.0靏/L 范围内呈线性关系；检出限为2.0靏/L 。本法选择性好，用于脚癣药水中水杨酸的测定，结果满意。

A highly sensitive and selective fluorimetric method has been developed for the determination of trace salicylic acid with 2', 7'-dichlorofluorescein as the fluorogenic reagent (lambda (ex) = 505, lambda (em) = 520 mn) at pH 5.5 similar to 7.0. Br- reacts with BrO3- in sulfuric acid solution (0.5 mol/L) to produce bromine (Br-2), which then reacts with 2', 7'-dichlorofluorescein resulting in fluorescence quenching;. In the presence of salicylic acid, the fluorescence intensity of the solution increases with increasing concentration of salicylic acid. The linear range is 2.0 similar to 48 mug/L, the detection limit is 2.0 mug/L. It has been applied to the determination of salicylic acid in tinea tincture with satisfactory result.