3D spongy-like Au film for highly stable solid contact potentiometric ion selective electrode: application to drug analysis

Abstract

Potentiometric ion selective electrodes with simple design and high potential stability are required for in-line process, clinical and quality control analysis. The objective of this work is to develop a high-surface-area Au nanostructure solid-contact (SC) platform for high stable ion selective electrode for drug analysis. Memantine, a pharmaceutical compound prescribed for Alzheimer’s disease, with challenging measurable analytical characteristics, was selected as a model for this purpose. Internal solid-contact with a high surface area was prepared by direct electrochemical deposition of Au-nanostructures onto a Pt electrode (500 µm diameter and 3 mm long). The proposed design combines the small size with the high surface area that is necessary for stable potential response. Cyclic voltammetry, impedance electrochemical spectroscopy and chronopotentiometry were used to evaluate electrochemical properties of the Au film. The Au-nanostructure SC electrode was coated with a membrane cocktail containing a lipophilic ion exchanger. The electrode exhibited a Nernstian response (58.5 ± 1 mV/decade) to memantine over a wide concentration range (1 × 10−5–1 × 10−2 M). The electrode showed high potential stability (0.03 µV/s), wide pH working range (3.0–8.0) and high selectivity to memantine $$\left( {\log k_{i,j}^{pot} \le - 2.38} \right)$$ . The electrode was applied for direct determination of memantine in pharmaceutical dosage form, human urine and surface water with high accuracy (± 2%) and precision (RSD ≤ 1.5%).