Quantification of total mercury in samples from cement production processing with thermal decomposition coupled with AAS

Abstract

This work aimed to assess the efficiency of a portable total mercury (Hg) analyzer (Lumex RA-915 +) that employs direct thermal decomposition atomic absorption spectrometry (AAS) to liberate Hg from a sample matrix as well as validate the quantification method of total Hg in different materials that are used in cement production. Regarding the solid matrix of the samples, the approaches included matrix-matched certified reference materials (CRM) calibration and adding a standard calibration solution to the solid samples. While both calibration approaches were suitable for the instrumentation employed, the uncertainty of the Hg mass fraction in a CRM and the need to include several matrix CRMs that differed in analyte content added to the complexity of the case. Spiked calibration is an acceptable alternative to calibration because it provides a lower expanded uncertainty at 15 %, 15.5 %, and 21.7 %, for the highest (> 200 ng), middle (50–150 ng), and lowest (< 50 ng) concentration ranges, respectively, compared to matrix CRM calibration. The obtained expanded uncertainty, the minimal requirements for sample preparation, easy and straightforward calibration and measurement, and high sample output indicate that the quantification of total Hg with thermal decomposition coupled with AAS is suitable for materials that are used in cement production.