以固绿FCF或茜素红作反应剂分光光度法测定城市土壤中的铬

Spectrophotometric Determination of Chromium in Urban Soil with Alizarin Red or Fast Green FCF as Reactant

在盐酸介质中,铬(Ⅵ)氧化固绿FCF使其褪色导致在最大吸收波长628nm处的吸光度下降;而在相同介质中,铬(Ⅵ)使茜素红氧化而显色,导致在其最大吸收波长520nm处的吸光度增加。上述褪色反应的吸光度下降幅度和显色反应的吸光度增加幅度分别与铬(Ⅵ)的质量浓度在0.2~4.0 mg·L^(-1)和0.5~14 mg·L^(-1)内呈线性关系,其检出限(3s/k)分别为0.014,0.051mg·L^(-1)。据此,分别应用上述两种方法测定了城市土壤中铬(Ⅵ)的含量,测定结果与电感耦合等离子体原子发射光谱法测得的结果一致。

In HCl medium, fast green FCF was oxidized by Cr（VI） resulting a color-fading reaction and leading to decrease of absorbance at its absorption peak of 628 nm, while alizarin red was oxidized by Cr（ VI ） to give a color reaction leading to increase of absorbance at the absorption peak of 520 nm. Linear relationships between the magnitude of decrease in absorbance （of the color-fading reaction） or the magnitude of increase in absorbance （of the color reaction） and the mass concentration of Cr（VI） were found in the ranges of 0. 2 to 4. 0 mg·L^-1 and 0. 5 to 14 mg· L^- 1 with values of detection limits （3s/k） of 0. 014, 0. 051 mg· L^-1 respectively. Based on these facts, the 2 methods described above were applied to the determination of Cr（VI） in urban soil samples separately, giving results in consistency with those found by ICP-AES.