The degradation of sulfacetamide with the formation of sulfanilamide leads to a deterioration in the quality of pharmaceuticals. In this work, potentiometric sensors for the simultaneous determination of sulfanilamide, sulfacetamide and inorganic ions, and for assessing the degradation of pharmaceuticals were developed. A multisensory approach was used for this purpose. The sensor cross-sensitivity to related analytes was achieved using perfluorosulfonic acid membranes with poly(3,4-ethylenedioxythiophene) or polyaniline as dopants. The composite membranes were prepared by oxidative polymerization and characterized using FTIR and UV-Vis spectroscopy, and SEM. The influence of the preparation procedure and the dopant concentration on the membrane hydrophilicity, ion-exchange capacity, water uptake, and transport properties was investigated. The characteristics of the potentiometric sensors in aqueous solutions containing sulfanilamide, sulfacetamide and alkali metals ions in a wide pH range were established. The introduction of proton-acceptor groups and π-conjugated moieties into the perfluorosulfonic acid membranes increased the sensor sensitivity to organic analytes. The relative errors of sulfacetamide and sulfanilamide determination in the UV-degraded eye drops were 1.2 to 1.4 and 1.7 to 4%, respectively, at relative standard deviation of 6 to 9%.

Nafion‐117/PEDOT composite membranes were synthesized by in situ chemical polymerization of 3,4‐ethylenedioxythiophene (EDOT) using ammonium persulfate as an oxidant. The polymerization of EDOT in Nafion membranes for various EDOT/oxidant treatment sequences was studied for the first time. PEDOT introduction leads to a slight decrease in both the ion‐exchange capacity and water uptake of the composite membranes, as well as to an increase in cationic transport. Membranes initially treated with an oxidant exhibit better conductivity and lower hydrogen permeability. The effect of both modification of Nafion‐117 membranes by PEDOT and hot‐pressing of hydrogen‐oxygen membrane‐electrode assemblies (MEAs) on the performance of proton‐exchange membrane fuel cells was studied. The maximum power density of the fabricated MEAs increases 1.5‐fold: from 510 (for a pristine Nafion‐117 membrane) to 810 mW cm−2 (for a membrane modified by PEDOT). The current density at a voltage of 0.4 V reaches 1248 and 2246 mA cm−2, respectively.

A novel potentiometric multisensory system for the analysis of sulfamethoxazole and trimethoprim combination drugs was developed. The potentiometric sensors (Donnan potential (DP) was used as an analytical signal) with an inner reference solution were based on perfluorosulfonic acid (PFSA) membranes modified with polyaniline (PANI) by in situ oxidative polymerization. The order of the membrane treatment with precursor solutions and their concentrations was varied. Additionally, the PFSA/PANI composite membranes were hydrothermally treated at 120 °C. The influence of the preparation conditions and the composition of membranes on their sorption and transport properties was studied. We estimated the factors affecting the sensitivity of DP-sensors based on the PFSA/PANI composite membranes to ions of sulfamethoxazole and trimethoprim simultaneously presented in solutions. A developed multisensory system provided a simultaneous determination of two analytes in aqueous solutions without preliminary separation, derivatization, or probe treatment. The re-estimation of the calibration characteristics of the multisensory system did not show a statistically significant difference after a year of its use. The limits of detection of sulfamethoxazole and trimethoprim were 1.4 × 10−6 and 8.5 × 10−8 M, while the relative errors of their determination in the combination drug were 4 and 5% (at 5 and 6% relative standard deviation), respectively.

Cross sensitivity of potentiometric PD sensors (sensors whose signal is Donnan potential) based on MF 4SC and Nafion cation exchange membranes containing hydrated ZrO 2 nanoparticles to amino acid (glycine, alanine, and leucine) ions in alkaline solutions has been investigated. By varying ZrO 2 concentra tions, it is possible to select pairs of PD sensors that have a sufficiently high sensitivity to the amino acid anions and K + cations in Gly + KOH, β Ala + KOH, and Leu + KOH solutions, as well as the lowest corre lation between responses of sensors. The pairs of PD sensors were used for simultaneous determination of amino acid anions and K + cations in alkaline solutions.

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