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本文研究了在盐酸溶液中砷(Ⅲ)—碘酸钾—溴化钾—甲基红褪色反应及影响褪色速度的因素,建立了动力学分光光度法测定水样中微量砷(Ⅲ)的新方法。方法灵敏度为2.4×10~(-9)克砷(Ⅲ)/毫升,测定范围0～11微克砷(Ⅲ)/25毫升,并具有操作简便、快速,分析结果稳定,分析费用低廉等特点。动力学法测定微量砷(Ⅲ),国外已有报导。本工作发现了在盐酸介质中,砷(Ⅲ)—碘酸钾—溴化钾—甲基红的褪色反应,其褪色速度可用log(A_0/A)值表示。其中A_0为无砷(Ⅲ)参加反应的吸光度;A为有砷(Ⅲ)参加反应的吸光度。通过实验证明,log(A_0/A)值与砷(Ⅲ)含量在一定范围内呈线性关系。本文详细地研究了影响褪色速度的条件,建立了动力学分光光度法测定微量砷的新方法。应用本方法测定水样中的微量砷(Ⅲ),获得了满意的结果,兼有操作简便、快速等特点。
In this paper, the fading reaction of arsenic (Ⅲ) - potassium iodate - potassium bromide - methyl red in hydrochloric acid was studied, and the factors affecting the fading speed were studied. The kinetic spectrophotometric method for the determination of trace arsenic (Ⅲ) method. The method has the sensitivity of 2.4 × 10 -9 g / ml and the determination range of 0 ~ 11 μg / ml. The method has the advantages of simple and rapid operation, stable analytical results and low analytical cost. Kinetic determination of trace arsenic (Ⅲ), foreign reports have been. The fading reaction of arsenic (Ⅲ) -potassium iodate-potassium bromide-methyl red in hydrochloric acid medium was found. The fading rate of arsenic (Ⅲ) was expressed as log (A_0 / A) Where A_0 is the absorbance of the reaction without arsenic (Ⅲ); A is the absorbance of the reaction with arsenic (Ⅲ). The experimental results show that the value of log (A_0 / A) is linear with the content of arsenic (Ⅲ) in a certain range. In this paper, the conditions affecting the fading speed were studied in detail, and a new method for the determination of trace arsenic by kinetic spectrophotometry was established. This method has been applied to the determination of trace arsenic (Ⅲ) in water samples with satisfactory results. Both of them are easy to operate and fast.