电感耦合等离子体质谱法测定铁铬铝合金中14种稀土元素

铁铬铝合金(Fe-Cr-Al)是一种优良的电热合金,冶炼时常加入一定量的稀土元素以提高产品的使用性能。用盐酸(1+1)溶样,建立了电感耦合等离子体质谱法(ICP-MS)测定14种稀土元素的方法。考察了采样深度对质谱强度、氧化物产率和二价离子产率的关系,选择13.5～14.5 mm为适宜的采样深度范围;选择¹³⁹La、¹⁴⁰Ce、¹⁴¹Pr、¹⁴⁶Nb、¹⁴⁷Sm、¹⁵³Eu、¹⁵⁷Gd、¹⁵⁹Tb、¹⁶³Dy、¹⁶⁵Ho、¹⁶⁶Er、¹⁶⁹Tm、¹⁷²Yb、¹⁷⁵Lu为测量同位素避免了质谱干扰,同时采用干扰系数校正法校正了¹⁷OH¹⁴⁰Ce对¹⁵⁷Gd的干扰;通过减少称样量和稀释以及¹⁰³Rh和¹⁸⁵Re双内标校正法消除了仪器漂移或基体效应产生的影响。在优化的条件下进行测定,校准曲线线性相关系数均达到了0.999 9 以上;各待测同位素检出限为0.002~0.083 μg/g,方法定量限为0.01~0.42 μg/g。按照实验方法测定3个铁铬铝合金样品中La、Ce、Pr、Nb、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu,测定结果的相对标准偏差(RSD,n=10)为0.48%~9.7%,加标回收率为93%~108%。采用电感耦合等离子体原子发射光谱法(ICP-AES)进行方法对照试验,结果表明,两种方法对样品中La和Ce测定的结果基本一致。

Determination of fourteen rare earth elements in iron-chromium-aluminum alloy by inductively coupled plasma mass spectrometry

Iron-chromium-aluminum alloy (Fe-Cr-Al) is an excellent electric heating alloy. Certain amounts of rare earth elements are often added during smelting to improve the use performance of products. The sample was dissolved with hydrochloric acid (1+1). The determination method of fourteen rare earth elements by inductively coupled plasma mass spectrometry (ICP-MS) was established. The relationship of sampling depth to mass spectrometric intensity, oxide yield and divalent ion yield was studied. The appropriate sampling depth range was 13.5-14.5 mm. ¹³⁹La, ¹⁴⁰Ce, ¹⁴¹Pr, ¹⁴⁶Nb, ¹⁴⁷Sm, ¹⁵³Eu, ¹⁵⁷Gd, ¹⁵⁹Tb, ¹⁶³Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ¹⁷²Yb and ¹⁷⁵Lu were selected as the measuring isotopes to avoid the mass spectrum interference. Meanwhile, the interference coefficient correction method was used to correct the interference of ¹⁷OH¹⁴⁰Ce to ¹⁵⁷Gd. The influence of instrument drift or matrix effect was eliminated by reducing the sampling amount, dilution and double internal standard calibration (¹⁰³Rh and ¹⁸⁵Re). Under the optimized conditions, the linear correlation coefficients of calibration curves were all above 0.999 9. The limits of detection (LOD) of testing isotopes were in range of 0.002-0.083 μg/g, and the limits of quantification (LOQ) were in range of 0.01-0.42 μg/g. The experimental method was applied for the determination of La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu in three Fe-Cr-Al alloy samples. The relative standard deviations (RSD, n=10) of determination results were between 0.48% and 9.7%, and the spiked recoveries were between 93% and 108%. The method of inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for comparison study. The determination results of La and Ce by two methods were basically consistent.