Voltammetric determination of phenylephrine hydrochloride using a multi-walled carbon nanotube-modified carbon paste electrode

Abstract

A chemically modified carbon paste electrode (CPE) was designed by mixing graphite and multi-walled carbon nanotubes (MWCNT). The electrochemical behaviour was studied, and the determination method of phenylephrine hydrochloride (PHE) on this sensor was established. According to the results, the optimal ratio of MWCNTs was approximately 12.5% (w/w). MWCNT-modified carbon paste electrodes (MWCNT-CPEs) showed high electrochemical activity for PHE, producing a sharp oxidation peak current (Ip) at approximately +0.816 V versus a saturated calomel electrode (SCE) reference electrode in phosphate buffer solution (PBS, pH 6.45), and the Ip increased by approximately two times compared to that of the bare CPE. The anodic Ip was linearly related with 5.0 × 10-6-7.5 × 10-4 mol l-1 PHE, with a detection limit of 3.7 × 10-7 mol l-1. Furthermore, MWCNT-CPEs were successfully applied to the determination of PHE in injection, eye drop and nasal spray liquid samples as a simple, rapid and low-cost method.