Sensing and characterization of neurotransmitter 2-phenylethylamine based on facilitated ion transfer at solvent polymeric membranes using different electrochemical techniques

Abstract

Square Wave Voltammetry (SWV), chronoamperometry and chronocoulometry are exploited to take advantage of their different performance characteristics in the determination, characterization and sensing of the neurotransmitter 2-phenylethylamine (PEA), based on the ion transfer of its protonated form at a solvent polymeric membrane facilitated by dibenzo-18-crown-6 (DB18C6). The general voltammetric features characterizing the PEA+ transfer are established by SWV and the standard ion transfer potential, diffusion coefficient and complexation constant value between PEA+ and DB18C6 are calculated from the SWV recordings. Next, the performance of double pulse chronoamperometry and double pulse chronocoulometry for the determination of PEA based on its facilitated ion transfer is studied. Limits of detection between 3.6 and 9.2 µM for chronoamperometry and 1.7 and 2.7 for chronocoulometry are obtained. The influence of common ions on both chronoamperometric and chronocoulometric determination is also considered. The sensitivity ratio values found between foreign cations and PEA+ are 0.05, 0.3 and 0.2 for Na+, K+ and H+, respectively, whereas no interference was observed for Li+. In addition, the electrode is tested as a sensor for monitoring PEA+ concentration using a pulsed-amperometric mode. Interestingly, a simple procedure to extend the range of linear response of quantitative electrochemical techniques significantly based on a previous analysis of chronoamperometric recordings is proposed and successfully tested.