β修正──铬天青S新光度法测定水和食品中铁

Determination of iron with chrome azurol S by β correction spectrophotometry

在pH4缓冲溶液中，铁（Fe^(3+)）与铬天青S（CAS）作用，显色液由黄色变蓝色。β修正新光度法测定痕量铁能够消除过量铬天青S干扰，使修正吸光度A_β与铁浓度（x）呈线性关系，从而提高分析灵敏度。实验表明，相对标准偏差RSD≤3.8％，回收率91.3%～109％。铁最低测定浓度0.015mg／L。该方法适合于水和食品中铁测定。

In pH4 solution,iron (Fe^(3+)) can react with chrome vazurol S (CAS)and the color of the reacted solu tion changes from yellow to blue color.In this paper β correction new spectrophotometry was used to deter mine trace amounts of Fe.It can eliminate the effect of surplus CAS in such a coloured solution to show lin ear relation between β correction absorbance (A_β) and Fe^(3+) concentration (x) and to increase the analytical sensitivity.Experiments showed that RSD was less than 3.8% and the recovery rate was 91.3%～109%.The minimum determination concentration of Fe^(3+) is 0.015mg/L.The method is applicable to analyse iron in water and food.