Simultaneous quantification of dopamine, acetaminophen and tyrosine at carbon paste electrodes modified with porphyrin and clay

Abstract

A Cameroonian smectite clay collected in a deposit on Sabga hill (West Cameroon, Central Africa – denominated as Sa) and a metal free meso-tetra(4-carboxyl phenyl)porphyrin (shortened as TCPP) were used to modify carbon paste electrodes. They were then exploited for the simultaneous electrochemical detection of dopamine (DA), acetaminophen (AC) and tyrosine (Tyr). Square wave voltammetry (SWV) revealed an increase in oxidation peak responses along with a negative shift of the corresponding anodic peak potentials for DA, AC and Tyr when using a carbon paste electrode modified with clay and porphyrin (TCPP–Sa/CPE), in comparison with those obtained at carbon paste electrodes modified with either clay (Sa/CPE) or porphyrin (TCPP/CPE). The TCPP–Sa/CPE exhibited attractive characteristics such as extended linear ranges, high sensitivities and selectivities, and low limits of detection for DA (0.1 μM), AC (0.2 μM) and Tyr (0.7 μM), using square wave voltammetry. The developed sensors were applied to the determination of AC in a pharmaceutical preparation and simultaneously DA, AC and Tyr in human urine.