2’,7’-二氯荧光素荧光法测定环境样品中微量As(Ⅲ)的研究

Studies on Fluorimetric Method for the Determination of Trace Arsenic(Ⅲ) with 2′,7′-Dichlorofluorescein

本文报道了以 2’,7’ -二氯荧光素为指示剂 ,荧光法间接测定微量 As3+ 的新方法。在 p H=5 .5～ 7.5中性缓冲介质中 ,I2 与 2’,7’ -二氯荧光素反应 ,使 2’ 7’ -二氯荧光素的荧光猝灭 ,当加入 As3+与 I2 反应使体系荧光增强 ,体系激发波长和发射波长分别为λex=5 0 8nm,λem=5 2 4nm。As3+含量在 1.0～ 80 μg· L- 1范围内呈良好线性关系 ,检测限为 1.0 μg·L- 1 。该方法灵敏度高 ,选择性好 ,用于工业废水和河水样品微量 As3+ 的测定 ,结果满意。

A rapid,simple and sensitive fluorimetric new me thod has been developed for the determination of trace amounts of arsenic (Ⅲ) w ith 2′,7′-dichlorofluorescein as fluorogenic reagent (λ ex =5 08 nm ,λ em =524 nm ) at pH 5.5—7.5.In a neutral medium, I 2 reacts with 2′,7′-dichlorofluoresce to produce a non-fluorescence com pound.If arsenic (Ⅲ) is present,the fluorescence intensity of the solution incr eases with the increasing concentration of As- 3+ when appropriate amoun ts of I 2 and 2′,7′-dichlorofluorescein are added.A linear calibration cu rve was obtained in the range of 1.0—80.0 μg·L- -1,the detection limi t is 1.0 μg·L- -1.It has been applied to the determination of As- 3+ in the waste water and river water with satisfactory results.