探讨了盐酸羟胺-钼(V)-EDTA络合物掩蔽钼,硫脲-铼-氯化亚锡分光光度法选择性测定含钼粗铼酸钾中铼含量的方法。对盐酸羟胺-钼(V)-EDTA掩蔽钼的体系及对硫脲-铼(II)-氯化亚锡络合物显色的条件进行了优化。结果表明:于弱盐酸介质中,80℃水浴35min条件下,4mLEDTA溶液和3mL盐酸羟胺溶液能够掩蔽3.0mg钼,且络合掩蔽体系对显色络合物无影响;于3.0mol/L盐酸介质中,在吸收波长λ440nm处,铼质量浓度在O~20ug/mL范围内符合比尔定律,检出限为1.91×10μg/mL。方法用于含钼40%~50%的粗铼酸钾样品中10%~20%的铼含量测定,相对标准偏差(RSD,n=7)为0.15%~0.25%,回收率为100%。
A method for selective determination of rhenium in raw potassium rhenate containing molyb- denum was proposed by thiourea-rhenium( II )-stannous chloride spectrophotometry after masking mo- lybdenum with hydroxylamine hydrochloride-molybdenum (V)-EDTA complex. The conditions for masking molybdenum with hydroxylamine hydrochloride-molybdenum ( V )-EDTA and the coloring conditions for thiourea-rhenium ( II )-stannous chloride were optimized. The results showed that, in weak hydrochloric acid, 3.0 mg of molybdenum could be masked with 4 mL of EDTA solution and 3 mL of hydroxylamine hydrochloride solution in water bath at 80 ℃ for 35 min. Moreover, the compl- exation masking system had no influence on the coloring complex. In 3.0 mol/L hydrochloric acid me- dium, the Beer's law was obeyed for mass concentration of rhenium in range of 0-20 μg/mL at A440 nm. The detection limit was 1.91× 10 8 μg/mL. The proposed method was applied to the determina- tion of rhenium (10%-20%) in raw potassium rhenate sample containing molybdenum (40%-50%), The relative standard deviation (RSD, n=7) was 0.15%-0.25%, and the recoveries were 100%.