[Studies on fluorimetric method for the determination of trace arsenic (III) with 2',7'-dichlorofluorescein]

A rapid, simple and sensitive fluorimetric new method has been developed for the determination of trace amounts of arsenic (III) with 2',7'-dichlorofluorescein as fluorogenic reagent (lambda ex = 508 nm, lambda em = 524 nm) at pH 5.5-7.5. In a neutral medium, I2 reacts with 2',7'-dichlorofluoresce to produce a non-fluorescence compound. If arsenic (III) is present, the fluorescence intensity of the solution increases with the increasing concentration of As3+ when appropriate amounts of I2 and 2',7'-dichlorofluorescein are added. A linear calibration curve was obtained in the range of 1.0-80.0 micrograms.L-1, the detection limit is 1.0 microgram.L-1. It has been applied to the determination of As3+ in the waste water and river water with satisfactory results.