Inhibitory Fluorophotometric Determination of Trace Amount of Mercury in Simulated Wastewater

It was found that in Na2HPO4-citric acid buffer medium of pH 8.00, the oxidation of p-cresol by hydrogen peroxide was strongly catalyzed by haemoglobin (Hb), leading to an enhancement of fluorescence. The indicator reaction was inhibited by the presence of Hg(Ⅱ). Based on these facts, the determination of trace amount of Hg(Ⅱ) in simulated wastewater by inhibitory spectrofluorimetry was proposed. The optimized conditions found were as follows: ① concentration of Hb: 2.00×10-7mol·L-1; ② concentration of p-cresol: 1.60×10-3mol·L-1; ③ concentration of H2O2: 1.11×10-3mol·L-1; ④ time of reaction: 80 min. Linear relationship was found between values of ΔF(F0-F) determined at wavelengths of 318 nm (λex) and 405 nm (λem) and concentration of Hg(Ⅱ) in the range of 2.00×10-8-1.00×10-5mol·L-1. The proposed method was used in the analysis of simulated wastewater, giving values of recovery and RSD′s (n=8) in the ranges of 94.0%-105% and 2.5%-3.3%.