Multivariate optimization of a novel potentiometric sensor to determine silver ions in real water and pharmacological product samples

In this work, a selective potentiometric sensor was developed using a carbon paste electrode (CPE) as an indicator electrode to determine silver ions in real water and pharmacological samples. A Schiff base, ( E )-4-[[(8-aminonaphthalen-1-yl)imino]methyl]-5-(hydroxymethyl)-2-methylpyridin-3-ol, was synthesized and utilized as a highly selective ionophore in the CPE composition. The percentage of the CPE composition, such as MWCNTs as a modifier, graphite powder, paraffin oil as a binder and Schiff base, was optimized by D-optimal mixture design to decrease the number of experimental runs, cost, and reagent consumption. This sensor indicated the Nernstian slope (59.7 mV/decade), pH range of 3.51–7.33, and response time of 5 s for the Ag(I) ion determination under the optimum CPE composition. Besides, the sensor showed a wide linear range of 1 × 10 –5 to 1 × 10 –1 M with a detection limit of 1.1 × 10 –6 M for the Ag(I) ion measurement. Finally, the sensor was applied as an indicator electrode in the potentiometric titration of Ag(I) ions with KI as a titrant. The sensor was also used to analyze tap water and silver sulfadiazine cream samples with an appropriate recovery (92.6–97.8%) and low RSDs (1.5–3.9%). Graphical abstract