银的野外快速分析方法——巯基棉富集-Ag-TMK-DBS三元络合物光导比色法

发展了一种能在野外测定0.25~1000μg/g银量的Ag-TMK-DBS三元络合物光导比色测定法。样品经硝酸封闭溶解后,用巯基棉富集分离银,在pH 4.5的乙酸-乙酸钠缓冲介质中,银与硫代米蚩酮(TMK)-十二烷基苯磺酸钠(DBS)形成易溶于水的红色三元胶束络合物,用自行开发研制的光导(比色)分光光度计比色测定痕量银。方法检出限为0.10μg/g,加标回收率为96.0%~99.4%,11次测定的精密度(RSD)小于5.76%。方法较为快速、简便、准确和灵敏,经国家一级标准物质验证,分析结果与标准值吻合。用光导分光光度计测定,准确度和精密度均有很大改进,结果与室内原子吸收光谱分析结果一致。方法具有广阔的应用前景。

Rapid Field Analysis of Silver by Sulfhydryl Cotton Preconcentration- Fiber Optic Spectrophotometry with Ag-TMK-DBS Ternary Complex

A rapid field fiber-optic spectrophotometric method for determination of silver based on the chromogenic reaction of silver with TMK-DBS was developed.The sample was digested with nitric acid and sulfhydryl cotton was added into the sample solution to separate Ag from the interference elements.In buffer solution of HAc-NaAc(pH 4.5),Ag reacted with TMK and DBS to form a water-soluble red ternary complex.Absorbance of the ternary complex was determined by a fiber-optic spectrophotometer at 540 nm.Some factors affecting the silver analysis were studied.The detection limit(3s)of method was 0.10 μg/g for Ag.The recovery of the method was 96.0%～99.4% with precision of less than 5.76% RSD(n=11).The method has been applied to the determination of silver in National Standard Reference samples.The results are in agreement with certified values and comparable with those from the indoor analysis by AAS in accuracy and precision.