Potentiometric determination of pH values of dilute sulfuric acid solutions with glass combination electrode equipped with ionic liquid salt bridge

Application of a pH Electrode Incorporating an Ionic Liquid Salt Bridge to the Measurement of Rainwater Samples

“…The pH15 values obtained with IL-E are much closer to the theoretical pH values for the dilute sulfuric solutions than those obtained with KCl-E. This tendency is consistent with the results obtained in a previous evaluation of IL-E. 24 The larger pH values obtained with KCl-E are ascribed to the following two factors: i) the residual liquid junction potential at the contact of the concentrated KCl solution with the sample solution; and ii) an increase in the ionic strength of the sample solution due to leakage of the concentrated KCl solution from the liquid junction. The response stabilized much faster with IL-E ( Table 1).…”

“…A prototype pH electrode incorporating ILSB 24 (denoted as IL-E from now) and a commercially available pH electrode with a ceramic plug type liquid junction (9611-10D, Horiba, Ltd., denoted as KCl-E) was used.…”

“…Due to the dissolution of hydrogen phthalate ions in the IL phase, a potential shift of a few mV was found when IL-E was calibrated with a phthalate standard solution. 21 Therefore, the 0.05 mol kg -1 citrate buffer solution (pH = 3.776 at 298 K) was used instead of the phthalate standard solution in case of IL-E. 23,24 The pH was measured three times for 15 min at 298 ± 0.2 K for each sample. The average pH value obtained after 15 min, pH15, was defined as the experimental pH value for each solution.…”

“…[16][17][18][19][20][21][22][23][24] This electrode utilizes a reference electrode based on a new type of salt bridge with a completely different working principle. The new salt bridge relies on the partition of an ionic liquid (IL) instead of the diffusion of a concentrated KCl solution.…”

“…The experimental pH values were in good agreement within 0.03 pH units of the theoretical pH values. 23,24 In this work, the applicability of a pH electrode incorporating ILSB to the measurement of rainwater pH was assessed. A superior response, compared to the conventional electrode, was confirmed in terms of the deviation from theoretical pH values, the response time, and the elimination of any sample contamination.…”