电感耦合等离子体原子发射光谱法测定铌铁合金中铌

Determination of niobium in niobium-iron alloy by inductively coupled plasma atomic emission spectrometry

铌铁样品以氢氟酸和硝酸消解,直接在氢氟酸介质中使用电感耦合等离子体原子发射光谱法（ICP-AES）测定铌含量。试验考察了共存基体元素铁以及常量杂质硅、钛、铝、钽等对测定的基体效应、光谱干扰以及背景噪声等因素的影响。通过采取优化样品稀释比例、选择适宜灵敏度分析谱线及其检测积分与背景校正区域,优化仪器工作条件等措施,将铌元素的检测信号强度调控在适宜水平,以确保方法具有良好线性范围以及精密度和正确度水平。试验采用基体匹配法绘制校准曲线,并进行同步背景校正,检验周期仅需10--15min。结果表明：在铌质量分数为50%--80%范围内,校准曲线线性相关系数r〉0.999 5。按照实验方法进行测定,实际铌铁合金样品测定结果的相对标准偏差（RSD,n=8）不大于0.2%;铌铁标准样品的测定结果与认定值一致;实际铌铁合金产品的测试结果与纸上色层分离重量法的测试结果也一致。

The niobium-iron alloy sample was dissolved with hydrofluoric acid and nitric acid. The content of nio- bium in hydrofluoric acid medium was directly determined by inductively coupled plasma atomic emission spectrom- etry（ICP-AES）. The influence of matrix iron and coexisting impurities including silicon, titanium, aluminum and tantalum on the matrix effect, spectral interference and background noise in determination was investigated. The dilution ratio of sample and the working conditions of instrument were optimized. The analytical lines with appropriate sensitivity as well as the detection integration and background correction area were selected. Consequently, the detection signal intensity of niobium was controlled at appropriate level to guarantee the good linear range, pre- cision and accuracy level of method. The calibration curve was drawn by matrix matching. Meanwhile, the back- ground correction was conducted synchronously. The detection period was only 10-15 min. The results showed that the linear correlation coefficient of calibration curve was r〉0. 999 5 when the mass fraction of niobium was in range of 50%-80 %. The proposed method was applied to actual determination, and the relative standard deviation （RSD, n=8） of the determination results for actual niobium-iron alloy sample was not more than 0.2%. The determination results of niobium-iron certified reference materials were consistent with the certified values. The determination results of actual niobium-iron sample were consistent with those obtained by paper chromatography gravlmetry.