Inhibitory Kinetic Photometric Determination of Traces of Arsenic in Environmental Water

It was found that in 1.0 mol·L-1 acetic aicd medium,the redox reaticon between rhodamine B and potassium persulfate was strongly catalyzed by Ag(Ⅰ) ion,leading to an enhancement of fading of color of the rhodamine B.This indicator reaction was inhibited by the presence of As(Ⅴ) ion. Influential factors,including the kinds and concentration of acid medium,amount of reagent,temperature and time of reaction,time of stability,and interferences of coexisting ions were studied.Linear relationship between values of lg(A0/A)and concentration of As(Ⅴ) ion was obtained within 80 μg·L-1 when measured at the absorption maximum of 554 nm.Detection limit (3S/N) of the method found was 1.23×10-6g·L-1.The proposed method was used in the determination of As(Ⅴ) ion in environmental water sample,giving values of recovery ranged from 95.5% to 102.8%,and values of RSD′s (n=9) in the range of 0.9%~3.9%.