Solid-contact ion-selective electrodes for potentiometric determination of phenylethylamine in vitro

Abstract

The implementation of all-solid-state ion-selective electrodes for phenylethylamine (PEA) determination is described in this paper. The electrode was constructed using 4-carboxyphenylboric acid as an ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)p-henyl]borate as an ion exchanger and 2-nitrophenyl octyl ether as a plasticizer in the selective polymeric membrane. The solid-contact conductive layer between the polymer layer and gold wire (0.5 mm diameter) was fabricated by electro polymerizing poly (3,4-ethylene dioxythiophene) doped with polystyrene sulfonate (PEDOT/PSS) for ion-to-electron transfer. The electrode exhibited a near-Nernstian response to PEA with the detection limit of 1 µM and stable responses in the pH operation range of 7.0–8.0 as well as the temperature range of 20 ∘C–40 ∘C. Experiments were carried out to investigate the response time, selectivity to common cations, reproducibility and life span of the developed electrodes. Fast response time of less than 8 s, good reproducibility and long-term stability were achieved by the electrodes. In addition, the electrode was tested in human plasma as background by using the standard addition method. The recovery rate close to 100% at 10−5 M PEA solution indicated the possibility to determine PEA in biologic fluids and pharmaceutical analyses.