Hypophosphite ReductionIodometric Titration of Arsenic in Ore Samples
摘 要
矿石样品(0.5 g)溶于硝酸盐酸(3+1)混合酸(20 mL)中,加硫酸(5 mL)并蒸发至冒三氧化硫白烟,冷却后加入盐酸(1+1)溶液70 mL,温热至盐类溶解后,用硫酸铜(0.1 g)作催化剂,加入次亚磷酸钠至过量约1~2 g,使砷(Ⅲ)还原至单体砷析出,过滤。将带有单体砷沉淀的滤纸投入烧杯中,加入过量碘标准溶液使砷溶解。在20 g·L-1碳酸氢钠溶液中,用硫代硫酸钠标准溶液滴定过量的碘;根据两标准溶液的消耗量计算样品中砷的含量。应用此方法分析了3个标准样品,所得结果与认定值相符,测定值的相对标准偏差(n=5)在1.5%~2.1%之间。
Abstract
The ore sample (0.5 g) is dissolved in 20 mL of HNO3HCl (3+1) mixed acid and fumed with 5 mL of H2SO4. After cooling, the salts are dissolved with 70 mL of warm HCl (1+1) solution. Arsenic (Ⅲ or Ⅴ) in the solution is reduced to elementary state by adding sodium hypophosphite with 1 to 2 g in excess using 0.1 g of CuSO4 as catalyst. After filtration and washing, the precipitate of elementary arsenic together with the filter paper is removed to the beaker and an excess and definite amount of iodine standard solution is added to dissolve the As° completely, and the excess amount of iodine is titrated with Na2S2O3 standard solution in a medium of 20 g·L-1 NaHCO3 solution. Based on the volume of the 2 standard solutions consumed in dissolution of As° and titration of excess of iodine, content of arsenic in the sample is calculated. Three standard samples were analyzed by the proposed method, and contents of arsenic found were in consistency with the certified values, with values of RSD′s (n=5) ranged from 1.5% to 2.1%.
中图分类号 O655.23
所属栏目 工作简报
基金项目
收稿日期 2013/5/17
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联系人作者赵树宝(shbzh@163.com)
备注赵树宝(1967-),男,安徽庐江人,工程师,主要从事化学分析。
引用该论文: ZHAO Shubao,ZHAO Jianwen. Hypophosphite ReductionIodometric Titration of Arsenic in Ore Samples[J]. Physical Testing and Chemical Analysis part B:Chemical Analysis, 2014, 50(6): 708~710
赵树宝,赵剑文. 次亚磷酸钠还原-碘滴定法测定矿石样品中砷含量[J]. 理化检验-化学分册, 2014, 50(6): 708~710
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参考文献
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【3】何英.砷化氢分离砷钼蓝分光光度法测定钨矿中的砷[J].冶金分析, 2005,25(1):60-62.
【4】王宁伟,柳天舒,朱金连,等.氢化物原子吸收光谱法测定磷矿石中的砷[J].冶金分析, 2008,28(4):68-69.
【5】孙致安,左正运,张敏,等.火焰原子吸收光谱法测定铜精矿中杂质砷[J].检验检疫学刊, 2003,9(6):32-33.
【6】王文林,戴晖,杨力,等.氢化物发生原子荧光光谱法测定土壤中的砷[J].理化检验化学分册, 2009,45(6):669-670.
【7】郭敬华,马辉,王水锋,等.原子荧光光谱法测定土壤和水系沉积物国家标准物质中砷[J].岩矿测试, 2009,28(2):182-184.
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