ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Gravimetric titrations in a modern analytical laboratory: evaluation of performance and practicality in everyday use

Lukáš Kejla, Petr Svoboda, Jan Sedláček, and Pavel Šimáček

Department of Petroleum Technology and Alternative Fuels, University of Chemistry and Technology Prague, Prague 6, Czech Republic

E-mail: Lukas.Kejla@vscht.cz

Received: 13 August 2021  Accepted: 27 November 2021

Abstract:

Titrations play a crucial role in quality assessment of inorganic chemicals and are still routinely done volumetrically with visual endpoint detection. These procedures require a significant amount of glassware, e.g., burettes designated for specific volumetric solutions, pipettes, volumetric flasks, the use of which presents many drawbacks such as liquid thermal expansion, liquid retention on the glass walls as well as poor readability. In recent years, the idea of gravimetric titrations, an old technique, where mass of the titrant is measured instead of the volume, has gained some traction among analytical chemists, as most disadvantages associated with volumetric titration can be solved by a switch to the gravimetric kind. In this study, six standardizations and six assays were carried out by gravimetric and volumetric titrations and the procedures were compared based on the combined standard uncertainty, repeatability, practical considerations and associated challenges. It was found that despite the low density and the large volume, there is no need to apply air buoyancy corrections to the titrants used for gravimetric titrations. These corrections, however, cannot be neglected for the mass of the standard and the sample when extremely accurate results are needed or if the densities of the two are vastly different. Gravimetric titrations outperformed the volumetric kind in both practicality and performance as was evident from the associated combined standard uncertainties. Also, there were no statistically significant differences between the mean assay results. For these reasons we recommend the use of gravimetric titrations for routine assays of inorganic chemicals.

Graphical abstract

Keywords: Gravimetric titration; Volumetric titration; Uncertainty; Statistical evaluation; Buoyancy correction

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02004-z

Chemical Papers 76 (4) 2051–2058 (2022)