A new method for the SI-traceable quantification of element contents in solid samples using LA-ICP-MS

Abstract

The present work introduces a novel approach for the quantitative and SI-traceable analysis of element contents in solid materials with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The laser ablation and the nebulizer system were connected to the torch using a y-piece. Several standard solutions having well-known element contents were introduced one after the other into the plasma simultaneously with the ablated material. In contrast to all other quantification methods the solid sample itself serves as the reference and the content of an analyte element was calculated based on the well-known content of the matrix element (like Si in a glass sample). Equations to describe the novel method were derived inspired by the standard addition method. To investigate the feasibility of the novel method, the contents of Pb and Rb were analysed in two commercially available standard reference materials (NIST SRM 610 and 612 glass samples). These solid samples were analysed together with solutions of different mass fractions of silicon as the reference element (R) and lead or rubidium as the analyte elements (A). The mass fractions of Pb and Rb measured in the two certified reference materials (CRMs) were equal to the certified values within the limits of their expanded uncertainties (U(w_x(A)) with k = 2). Compared to other quantification methods, this new method enables SI-traceability for the measurement results without the need to employ preferably matrix-matched solid reference materials, which will be a great benefit for the application of laser ablation in general, especially considering the extreme lack of matrix-matched CRMs. The new method is best-suited to determine impurities in highly pure samples with a mass fraction of the matrix element close to 1 g g⁻¹.