Sensitive and selective spectrofluorimetric determination of chromium(VI) in water by fluorescence enhancement

Abstract

A new fluorogenic method for the selective and sensitive determination of chromium(VI) in acidic water using rhodamine B hydrazide was developed. This method was based on the oxidation of non-fluorescent rhodamine B hydrazide by potassium dichromate in acidic aqueous conditions to give rhodamine B, which was highly fluorescent, as a product. With the optimum condition described, the fluorescence enhancement at 585 nm was linearly related to the concentration of chromium(VI) in the range of 5.0 × 10 −8 to 2.0 × 10 −6 mol L −1 (2.60–104 ng mL −1) with a correlation coefficient of R 2 = 0.9993 ( n = 18) and a detection limit of 5.5 × 10 −9 mol L −1 (0.29 ng mL −1). The R.S.D. was 2.2% ( n = 5). The proposed method was also applied to the determination of chromium(VI) in drinking water, river water and synthetic samples.