化学发光法测定镀铬废液及自来水中Cr(Ⅲ)

Determination of Cr (Ⅲ) in the Chromium-plating Waste and Tap Water by Chemiluminesceace Method

痕量Cr(Ⅱ)对H_2O_2在碱性介质中氧化鲁米诺的反应具有催化作用,反应过程中会发出波长为425 nm的光线,发光强度与Cr(Ⅱ)的含量成比例关系,据此可测定Cr(Ⅲ)。

Based on the catalytic action of trace Cr(Ⅲ) on the oxidation of luminol by hydrogen peroxide in an alkaline medium (pH 11.0), a chemilumi-nous method was described for the determination of Cr(Ⅲ) in the chromium-plating waste and tap water with Model HF-I intelligent chemiluminescence analyzer designed by the authors. During the reaction, a light of definite wavelength would emit, and its intensity was in proportion to the content of Cr(Ⅲ). The sensitivity of this method is high and the detection limit is 5×10-10 mol/l. The linear range is from 2.0×10-5 to 2.0×10-9 mol/l. The relative standard deviations are 2.55% and 5.13% for the chromium-plating waste and tap water respectively. The average recoveries are 99.4% and 98.0% for the chromium-plating waste and tap water respectively. 0.010 mol/1 EDTA solution can be used to mask Fe3+, Co2+, and Ni2+ ions which interfere the determination of Cr(Ⅲ).