Influence of ionic strength on the performance of glass electrodes for pH determination
Abstract
It was studied the impact of salinity, expressed in terms of ionic strength (I [mol L⁻¹]), on the pH value obtained with different commercial combined glass electrodes which were calibrated using buffer solutions designed by our group. Thus, three calibration buffer solutions with I = 0.10 mol L-1 and six with I = 0.72 mol L-1 imposed with NaCl were prepared and used, with the aim of emulating the effect of a marine matrix. These were potentiometrically titrated and the pH vs. v were analyzed using a method without approximations that uses a non-linear polynomial fit and without segmentation, generated from the single electroneutrality balance for each of the tests. From such adjustments, the effective molar concentration of the acid-base species that conforms to each buffer solutions, its pKa value, the exact pH value of these buffers under high salinity conditions, as well as the pKw value of the solvent were obtained.
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Copyright (c) 2023 Esperanza Elizabeth Vilchis-Barrera, Ricardo Galdino Martínez-Pérez, Arturo de Jesús García-Mendoza, José Alejandro Baeza-Reyes, Joan Albert Sánchez-Cabeza
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