A new spectrophotometric method for the determination of micro-amounts of Chromium(Ⅵ) was proposed based on the oxidation of Sudan Ⅰ by Chromium(Ⅵ) in hydrochloric acid medium.The optimal conditions were studied.The maximum absorption of Sudan Ⅰ was at 485 nm.The decrease of absorbance of Sudan Ⅰ resulted from its oxidation by Chromium (Ⅵ),and the linear relationship was established between the decrease of absorbance and Chromium (Ⅵ) concentration of 0.2～2.6 μg/mL.The equation of linear regression was A=0.207 0 C+0.002 35,coegicient of correlation was 0.996 0,apparent molar absorption coefficient was 6.09×104 L/cm·mol.The proposed method had been applied to oletermine Chromium (Ⅵ) in water samples,and the recovery rate was 97.1％～100.3％ and the RSD was less than 3.0％.%在盐酸介质中,依据六价铬离子(Cr(Ⅵ))氧化苏丹红Ⅰ使其褪色的原理提出了测定Cr(Ⅵ)离子的新方法,确定了最优的测定条件.在485 nm处,Cr(Ⅵ)离子在0.2～2.6 μg/mL范围内符合比尔定律,线性回归方程为A=0.207 0C+0.002 35,相关系数为0.996 0,表观摩尔吸光系数为6.09×104 L/(cm·mol).该方法可用于水样中的微量Cr(Ⅵ)离子的测定,回收率为97.1％～100.3％,RSD小于3.0％.
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