Improvement of the characterization uncertainty of a matrix-certified reference material for accurate measurement of HSiF mass fraction in industrial fluorosilicic acid by using a direct measurement procedure.

The role of metrology in the industrial and manufacturing sectors is of paramount importance to ensure informed decision-making whether for product quality control, process monitoring and R&D activities. However, to guarantee the quality and reliability of analytical measurements, the development and use of appropriate reference materials (CRMs) is essential. In particular, certified reference materials (CRMs) are extensively used to validate analytical methods in a multitude of applications, measure uncertainty, improve the accuracy of measurement data, as well as to establish the meteorological traceability of analytical results. In this paper, we report the improvement of the characterization uncertainty of an in-house matrix reference material by direct determination of the concentration of fluorosilicic acid recovered from the fertilizers production industry. The certified reference material was characterized by the potentiometric method as a novel and direct approach for the determination of HSiF concentration and the results were compared against a reference measurement procedure based on molecular absorption spectrophotometry (UV-VIS). The approach adopted in the work resulted in the improvement of the uncertainty of the CRM by decreasing the characterization uncertainty, which constitutes the major contribution to the overall uncertainty. The newly obtained characterization combined standard uncertainty was 2.0 g.kg, which gives an expanded uncertainty (k = 2 with a confidence interval of 95%) of the CRM of 6.3 g.kg instead of 11.7 g.kg reported in previous works. This improved CRM can be used to improve the uncertainty of the analytical methods used for the determination of HSiF mass fraction and, therefore, to improve the accuracy of measurement data.