水中钙的负催化分光光度测定法

Microanalysis of Calcium in Environmental Water by Negative Catalytic Spectrophotometry

目的探讨用动力学光度分析法检测水中的微量钙。方法在硫酸介质中,KBrO3能氧化偶氮胂I褪色,微量钙负催化该褪色反应,用分光光度法测定该负催化反应速度与钙浓度的定量关系,并根据此关系测定反应体系中的钙含量。结果研究了该负催化褪色反应的最佳条件及动力学性质,建立了负催化光度法测定微量钙的新方法。在硫酸介质中,于波长500nm处测出该方法检测钙浓度的线性范围为0.20～1.88mg/L,检出限为14.40μg/L,对800μg/L的标准钙溶液进行20次平行测定,RSD为1.7%。环境水样中钙测定的回收率为96.6%～102%,RSD为1.9%～2.6%。结论该方法简便、快速、准确,适合于环境水样中钙含量的测定。

Objective To determine trace calcium in environmental water with kinetic spectrophotometry. Methods AzoarsineⅠis oxidized by KBrO3 in diluted H2SO4 medium and a discolour reaction emerged, calcium has a negative catalytic effect on this reaction. The relationship between the speed of discolour reaction and the concentration of calcium was linear and the contents of calcium can be detected by spectrophotometer. Results The optimum condition and kinetic parameters are investigated in detail, a new negative catalytic spectrophotometry for determination of trace calcium in environmental water was established. In diluted H2SO4 medium, wavelength is 500 nm, the linear range and the detection limit of this method were found to be 0.20-1.88 mg/L and 14.40 μg/L respectively. 20 samples of 800 μg/L calcium standard solution were determined, the RSD was 1.7%. The method was applied to determine calcium in environmental water rate of recovery and RSD were obtained to be 96.6%-102% and 1.9%-2.6%. Conclusion This method has many advantages such as simple, rapid, precise and is suitable for the determination of trace calcium in environmental water.