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Berto S, Blasco S, Castellino L, Cvetkovski A, De Stefano C, Gama S, García-España E, Hermann P, Lando G, Marafante M, Meyer M, Plass W, Quinodoz L, Milea D. A tutorial on potentiometric data processing. Analysis of software for optimization of protonation constants. Anal Chim Acta 2024; 1303:342476. [PMID: 38609256 DOI: 10.1016/j.aca.2024.342476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 03/11/2024] [Accepted: 03/12/2024] [Indexed: 04/14/2024]
Abstract
Defining the distribution of the chemical species in a multicomponent system is a task of great importance with applications in many fields. To clarify the identity and the abundance of the species that can be formed by the interaction of the components of a solution, it is fundamental to know the formation constants of those species. The determination of equilibrium constants is mainly performed through the analysis of experimental data obtained by different instrumental techniques. Among them, potentiometry is the elective technique for this purpose. As such, a survey was run within the NECTAR COST Action - Network for Equilibria and Chemical Thermodynamics Advanced Research, to identify the most used software for the analysis of potentiometric data and to highlight their strengths and weaknesses. The features and the calculation processes of each software were analyzed and rationalized, and a simulated titration dataset of a hypothetic hexaprotic acid was processed by each software to compare and discuss the optimized protonation constants. Moreover, further data analysis was also carried out on the original dataset including some systematic errors from different sources, as some calibration parameters, the total analytical concentration of reagents and ionic strength variations during titrations, to evaluate their impact on the refined parameters. Results showed that differences on the protonation constants estimated by the tested software are not significant, while some of the considered systematic errors affect results. Overall, it emerged that software commonly used suffer from many limitations, highlighting the urgency of new dedicated and modern tools. In this context, some guidelines for data generation and treatment are also given.
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Affiliation(s)
- Silvia Berto
- Università di Torino, Dipartimento di Chimica, Via P. Giuria 7, 10125, Torino, Italy.
| | - Salvador Blasco
- Institute of Molecular Sciences, Departamento de Química Inorgánica, University of Valencia, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - Lorenzo Castellino
- Università di Torino, Dipartimento di Chimica, Via P. Giuria 7, 10125, Torino, Italy
| | - Aleksandar Cvetkovski
- Faculty of Medical Sciences, Goce Delcev Universit, Krste Misirkov Bb, PO 201, 2000, Štip, Macedonia
| | - Concetta De Stefano
- Università degli Studi di Messina, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, CHIBIOFARAM, V.le F. Stagno d'Alcontres, 31, 98166, Messina, Italy
| | - Sofia Gama
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139.7), 2695-066, Bobadela LRS, Portugal
| | - Enrique García-España
- Institute of Molecular Sciences, Departamento de Química Inorgánica, University of Valencia, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 40 Prague 2, Czech Republic
| | - Gabriele Lando
- Università degli Studi di Messina, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, CHIBIOFARAM, V.le F. Stagno d'Alcontres, 31, 98166, Messina, Italy
| | - Matteo Marafante
- Università di Torino, Dipartimento di Chimica, Via P. Giuria 7, 10125, Torino, Italy
| | - Michel Meyer
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078, Dijon, Cedex, France
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie, Friedrich Schiller University Jena, Humboldtstr 8, D-07743, Jena, Germany
| | - Lauryn Quinodoz
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078, Dijon, Cedex, France; University of Applied Sciences Western Switzerland HES-SO, Haute Ecole d'Ingénierie et d'Architecture, Pérolles 80, 1700, Fribourg, Switzerland
| | - Demetrio Milea
- Università degli Studi di Messina, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, CHIBIOFARAM, V.le F. Stagno d'Alcontres, 31, 98166, Messina, Italy
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Maslarska V, Tencheva J, Budevsky O. New approach in the treatment of data from an acid-base potentiometric titrationI. Monocomponent systems of monofunctional acids and bases. Anal Bioanal Chem 2003; 375:217-22. [PMID: 12560965 DOI: 10.1007/s00216-002-1671-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2002] [Revised: 10/11/2002] [Accepted: 10/25/2002] [Indexed: 11/27/2022]
Abstract
Based on precise analysis of the acid-base equilibrium, a new approach in the treatment of experimental data from a potentiometric titration is proposed. A new general formula giving explicitly the relation V=f([H(+)]) is derived, valid for every acid-base titration, which includes mono- and polyfunctional protolytes and their mixtures. The present study is the first practical application of this formula for the simplest case, the analysis of one monofunctional protolyte. The collected mV data during the titration are converted into pH-values by means of an auto pH-calibration procedure, thus avoiding preliminary preparation of the measuring system. The mentioned pH-calibration method is applicable also in water-organic mixtures and allows the quantitative determination of sparingly soluble substances (particularly pharmaceuticals). The treatment of the data is performed by means of ready-to-use software products, which makes the proposed approach accessible for a wide range of applications.
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Affiliation(s)
- Vania Maslarska
- Medical University Sofia, Faculty of Pharmacy, Department of Chemistry, Dunav st.2, Bulgaria
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