氢化物发生-原子荧光光谱法测定银精矿中铋

Determination of bismuth in silver concentrates by hydride generation atomic fluorescence spectrometry

银精矿在供需双方交易和生产工艺流程的确定时,其中相关元素如铋的含量起着重要的作用。实验对标准YS/T445.11—2001中溶样方法进行了改进,用氯酸钾-硝酸-氢氟酸-硫酸-盐酸溶样体系代替了氯酸钾-硝酸-硫酸-王水溶样体系进行溶样,以硫脲-抗坏血酸为预还原试剂,硼氢化钾为还原剂,5%(体积分数)盐酸为测定介质,实现了氢化物发生-原子荧光光谱法对银精矿中铋的测定。在选定的工作条件下,铋质量浓度在20.0～200.0 ng/mL范围内呈线性关系,相关系数为0.999 4。按照银精矿中主要共存元素的最大含量分别进行干扰试验,结果表明其对铋测定的干扰均可忽略。方法检出限为2×10-5μg/m L。对铋质量分数为0.010%～0.50%的银精矿样品进行测定,测定结果与火焰原子吸收光谱法和电感耦合等离子体原子发射光谱法结果基本一致,相对标准偏差(RSD,n=9)为1.9%～10.6%,回收率为99%～102%。

Silver concentrate played an important role in the transaction btween supply and demand as well as the determination of production process, in which the grade of silver and the content of related elements such as bismuth played an important role. Dissolution method of standard YS/T 445.11-2001 was improved by the experiment. The potassium chlorate-nitric acid-hydrofluoric acid-sulfuric acid-hydrochloric acid solution system was used instead of potassium chlorate-nitric acid-sulfuric acid-chloroazotic acid solution system to dissolve samples.The sample solution was prereduced by thiourea and ascorbic acid. The potassium borohydride was used as reductive agent. The hydrochloric acid of 5 %(volume fraction) was used as the measuring medium. Then the bismuth in silver concentrates was measured by the method of hydride generation-atomic fluorescence spectrometry. Under the selected working conditions, the mass concentration of bismuth in range of 20.0 ~ 200.0 ng/mL showed linear relationship with correlation coefficient of r=0.999 4. The interference tests were carried out according to the maximum content of main coexisting elements in silver concentrate, which indicated that the coexisting in samples did not interfere with the determination of bismuth. The detection limit was 2×10-5 μg/mL.When the silver concentrate sample was measured within a measurement range of Bi: 0.010 %-0.50 %, the results were compared with those of FAAS and ICP method. The results were basically the same. The relative standard deviations(RSD, n=9) of determination results were between 1.9 % and 10.6 %. The recovery were between 99 % and 102 %.