Polyvinyl chloride-based 18-crown-6, dibenzo18-crown-6 and calix-[6]-arene zinc(II)-potentiometric sensors

A chemically modified solid-state sensor for magnesium(ii) ions and esomeprazole magnesium potentiometric assay

The use of electrochemical sensors offers a simple, affordable solution with great reliability. Magnesium is a mineral that the body requires to function properly. It encourages preserving a stable pulse, strong bones, and healthy blood pressure. Herein, a novel ion-selective electrode using esomeprazole magnesium trihydrate as an ion-association complex was developed for magnesium(ii) ion determination in mineral water, drug substances, and pharmaceutical formulations. The electrode response was optimized in terms of plasticizer type, ion exchanger concentration, and membrane composition. To find the best sensor combination, the initial optimization research was performed using eight different sensors. A membrane containing 20% esomeprazole magnesium trihydrate, 36% carbon, and 44% o-Nitrophenyl Octyl Ether (NPOE) as a plasticizer yielded the best potentiometric response. The developed sensor demonstrated a Nernstian response with a slope of 29.93 ± 0.1 mV per decade in the concentration range of 1.41 × 10^-5 mol L^-1 to 1 × 10^-2 mol L^-1. Within a pH range of 5-8, it had a low detection limit of 4.13 × 10^-6 mol L^-1. When compared to the official method, there are no statistically significant differences.

The use of ion-selective membranes to study cation transport in hybrid organic-inorganic perovskites

Using a methylammonium selective membrane in conjunction with electrochemical impedance spectroscopy, we measured ion migration in methylammonium lead triiodide (MAPbI₃) with a millisecond (ms) time constant under illumination. These values were consistent with the reported values of ionic conduction in thin-film perovskite solar cells. We monitored an electrochemical impedance response arising from ionic conductivity through MAPbI₃ and a methylammonium selective layer. We could fit this complex impedance response to an intuitive circuit model, which revealed an ionic species moving on a ms time scale. Electrospray ionization mass spectrometry (ESI-MS) revealed direct chemical evidence of methylammonium diffusion into the ion-selective layer. We found no experimental evidence indicating the mobility of lead ions or protons, suggesting that the mobile species observed under illumination is likely methylammonium.