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

The implementation of all-solid-state ion-selective electrodes for phenylethylamine (PEA) determination was described. 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 (0.5mm 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 1µM and stable responses in the pH operation range of 7.0-8.0 as well as the temperature range of 20-40ffiC. The fast response time of less than 8s, selectivity to common cations, good reproducibility and life span were also investigated to be acceptable. In addition, the electrode was tested in human plasma as background by using the standard addition method. The recovery rate close to 100% at 10-5M PEA solution indicated the possibility to determine PEA in biologic fluids and pharmaceutical analyses.