Metrological evaluation of the certification of primary reference materials characterized by high-precision constant-current coulometry for the reliability of the titration analyses

Abstract

The use of pure materials in chemical analysis is currently in high demand due to the need to provide reliable measurement results. In the Electrochemistry Laboratory of the National Institute of Metrology from Brazil (Inmetro) is located the primary system of coulometry, which is considered the standard of the measurement for the amount of substance. The main function of this primary system is to certify primary reference materials to ensure reliability and metrological traceability for titration analyses. Some important certified reference materials (CRMs), homogeneous, stable, and characterized with an accurate property value have been developed. This work aims to present the stages for certifying the primary reference materials in a metrological approach: potassium hydrogen phthalate for acid-base titration, potassium chloride for precipitation titration, and potassium dichromate for redox titration. In addition, the key comparisons that were necessary to demonstrate the national traceability structure's equivalence for these CRMs' international recognition will be shown.

Implementation of Coulometric Titration System at Constant Current for Certification of Primary Reference Materials

“…This technique has been used to determine the purity of primary reference materials required by industry and in chemical testing laboratories [1]. Coulometry is one of the most widely used analytical techniques in research laboratories and National Metrology Institutes (NMI) worldwide due to its high precision and accuracy for measuring the trace level or purity of different materials [2].…”

Certification of a New Naringenin Reference Material by Coulometric Titrimetry Combined HPLC‐MS

“…Characterization of CRMs should employ absolute analysis methods (or called primary methods) as far as possible. Absolute analysis methods are generally divided into two kinds : one is based entirely on the physical standard methods, such as methods of reproducing SI units in physics; the other is mostly based on the physical standard, such as the gravimetric method , volumetric method , coulometry and isotope dilution mass spectrometry [9]. The latter ones, which are widely used in analytical chemistry, also have high accuracy and reliability.…”