结晶紫褪色光度法测定痕量镧

Spectrophotometric Determination of Trace Amount of Lanthanum by the Decolouring Reaction of Violet

基于在氯化十六烷基吡啶存在下,稀酸介质中,La(Ⅲ)催化KIO4氧化结晶紫的褪色反应,建立了一个测定痕量La(Ⅲ)的催化动力学光度分析法。讨论了酸度、试剂用量、温度、干扰离子等因素的影响,优化了反应条件。该方法的线性范围为0.02μg/mL～8.0μg/mL La(Ⅲ),检出限为0.012μg/mL La(Ⅲ)。将本方法用于催化剂中痕量镧的测定,回收率为96.0%～106.0%。

In the presence of cetylpyridium chloride,a sensitive method for the determination of lanthanum（Ⅲ） by kinetic spectrophotometry was established based on the catalytic effect of trace lanthanum（Ⅲ）on the discoloring reaction of crystal violet with potassium periodate.The influence of acidity,amounts of reagents,temperature and other factors on the reaction were discussed.The optimum conditions of the reaction were determined.The linear range was 0.20~8.0μg/mL of lanthanum,and the detection limit was 0.012μg/mL.The proposed method has been applied successfully to the determination of trace lanthanum in catalyst samples,and the recovery was between 96.0% to 106.0%.