灰吹富集-氯化钠电位滴定法测定贵铅中银

采取样品加铅块灰吹法于900℃灰吹炉中对贵铅中银进行富集,灰吹后得到合粒。用硝酸溶解合粒得到硝酸银溶液,最后用氯化钠电位滴定法分析硝酸银溶液中银含量,建立了灰吹富集-氯化钠电位滴定法测定贵铅中银的分析方法。对灰吹富集的实验条件进行了考察,确定灰吹方式为样品加铅块灰吹法、样品量为0.65g、铅块用量为25g。实验称取与样品中银含量相当的金属银,采用与样品相同的实验方法进行灰吹,以银的加入量与回收量的比值作为补正因子对样品中银在灰吹过程的损失进行了补正。探讨了贵铅样品中共存杂质元素(铅、锑、铋、铜、砷、碲、铁、镍、钯)对测定的干扰,结果表明,贵铅样品中共存杂质元素不干扰银的测定。将实验方法应用于贵铅实际样品中银的测定,测定结果的相对标准偏差(RSD,n=8)为0.38%~0.94%,加标回收率在99%~101%之间,所得结果与硫氰酸钾电位滴定法测定值相吻合。

Determination of silver in noble lead by cupellationenrichment-sodium chloride potentiometric titration method

The silver in noble lead was enriched by cupellation method after lead brick was added into the sample in cupelling furnace at 900℃. The compsite granule was obtained after cupellation treatment. Then it was dissolved with nitric acid to obtain silver nitrate solution. Finally, the content of silver in silver nitrate solution was determined by sodium chloride potentiometric titration method. Consequently, a determination method of silver in noble lead by cupellation enrichment-sodium chloride potentiometric titration method was established. The experimental conditions for cupellation enrichment were investigated. The cupellation treatment by adding lead into sample was selected: the mass of sample and lead was 0.65g and 25g, respectively. The metallic silver with similar content of silver in sample was used for cupellation according to the same experimental method. The mass ratio of added silver to recovered silver was used as correction factor to correct the loss of silver in sample during cupellation treatment. The interference of coexisting impurity elements (lead, antimony, bismuth, copper, arsenic, tellurium, iron, nickel and palladium) in noble lead with determination was discussed. The results showed that the coexisting impurity elements in noble lead did not interfere with the determination. The experimental method was applied for determination of silver in noble lead actual samples. The relative standard deviations (RSD, n=8) of determination results were between 0.38% and 0.94%. The recoveries ranged from 99% to 101%. The results were consistent with those obtained by potassium thiocyanate potentiometric titration method .