A similar-matrix-matched calibration strategy by using microsecond pulsed glow discharge mass spectrometry in the application of purity analysis of high purity lanthanum oxide

Abstract

Quantitative analysis method of impurities in high purity lanthanum oxide (La2O3) by microsecond pulsed glow discharge mass spectrometry (Pulsed-GD-MS) was established. A similar-matrix-matched calibration strategy, i.e., calibrating the GD-MS instrument with the relative sensitivity factors (RSFs) derived from a similar matrix (100% Cu) to the matrix (80% Cu + 20% La2O3) to be analyzed was proposed. The feasibility of using the similar-matrix-matched calibration strategy was demonstrated by investigating the matrix effect in Pulsed-GD-MS. The accuracy of the method was validated by using La2O3 RMs. Finally, 71 impurities in La2O3 were quantitatively measured by Pulsed-GD-MS by using both mixing method and modified secondary cathode technique, and the results of main impurities were validated by HR-ICP-MS. In comparison to HR-ICP-MS, it had more advantages for Pulsed-GD-MS to determine some elements, which was difficult to dissolve such as Pt and Au, easy to be contaminated such as K, and difficult to be ionized in the ICP ion source like Cl. Compared with the mixing method, the modified secondary cathode technique showed some advantages, such as simpler sample pre-treatment, less sample amount, lower risks of contamination and lower limits of quantification. The purity of La2O3 by subtracting 71 impurities from 100% was then measured by Pulsed-GD-MS. The results showed that the measurement uncertainty of purity using the similar-matrix-calibration strategy was almost one order magnitude lower than that using the calibration of commonly used StdRSFs due to the significantly reduced expanded uncertainty (cover factor k = 2) of impurities analysis to about 30%. [Display omitted]