Differential dynamic potentiometry with ion selective electrodes: A tool for drug fingerprinting

Abstract

Differential dynamic potentiometry (DDP) is a novel potentiometric technique, which consists of recording the dynamic potential difference between two ion-selective electrodes (ISEs). In this article, we describe its application to studying the dynamic contribution of beta-cyclodextrin (β-CD) to the potential response of drug-selective electrodes. Surprisingly, DDP responses in serial calibration mode were characteristic for each individual drug, and might serve as drug-fingerprints. Also, non-monotonic DDP responses were obtained using single concentration step experiments, and these were used for quantitative drug analysis. Theoretical simulations of the DDP responses based on a reported dynamic diffusion model allowed both types of the experimentally obtained signals to be predicted.