铋和二氧化锰共沉淀分离-火焰原子吸收光谱法测定铅锭中铋

铅锭样品经硝酸(1+3)溶解,分别用氨水和硝酸(1+3)调节溶液的pH值约为3.1,加入10mL 100g/L硝酸锰溶液,于70℃的温度下,在0.47~0.70mol/L硝酸中加入10mL10g/L高锰酸钾溶液并不断搅拌,利用二氧化锰与铋共沉淀的特性实现了铋与基体铅的分离,将过滤所得沉淀用盐酸双氧水混合酸(49+2)溶解,以10%~25%(V/V)盐酸为测定溶液介质,选择223.1nm为测定波长,建立了火焰原子吸收光谱法(FAAS)测定铅锭样品中铋的方法。在选定的仪器条件下,铋在0.50~5.00μg/mL范围内和其对应的吸光度呈良好的线性关系,相关系数r=0.999 8,铋的方法检出限为0.002 8μg/mL。干扰试验表明,铅锭中分离后余下的铅及其他元素不干扰对铋的测定。将实验方法应用于4个质量分数为0.000 39%~0.062%的铅锭标准样品中铋的测定,结果与认定值基本一致,相对标准偏差(RSD,n=11)在0.67%~8.1%之间,加标回收率为98%~102%。

Determination of bismuth in lead ingots by flame atomic absorption spectrometry after co-precipitation separation with bismuth and manganese dioxide

The lead ingot sample was dissolved with nitric acid (1+3). The pH of sample solution was adjusted to about 3.1 with ammonia and nitric acid (1+3). After adding 10 mL of 100 g/L manganese nitrate solution, 10 mL of 10 g/L potassium permanganate solution was added into 0.47-0.70 mol/L nitric acid at 70 ℃under stirring. The separation of bismuth from matrix lead was realized by the co-precipitation characteristic between manganese dioxide and bismuth. The precipitate was dissolved with hydrochloric acid-hydrogen peroxide mixture (49+2). The determination method of bismuth in lead ingots by flame atomic absorption spectrometry (FAAS) was established using 10%-25% (V/V) as determination medium and 223.1 nm as determination wavelength. Under the selected optimal instrumental conditions, the concentration of bismuth in range of 0.50-5.00 μg/mL showed good linearity to its corresponding absorbance with correlation coefficient of r=0.999 8. The detection limit of bismuth in this method was 0.002 8 μg/mL. The interference tests showed that the residual lead and other elements in lead ingots had no interference with the determination of bismuth. The experimental method was applied to the determination of bismuth in four lead ingot standard samples with mass fraction of 0.000 39%-0.062%. The found results were basically consistent with the certified values. The relative standard deviations (RSD, n=11) were between 0.67% and 8.1%. The recoveries were between 98% and 102%.