Development of a Highly sensitive Methionine Sensor based on Copper Phthalocyanine and Gold Nanoparticles-Modified Carbon Paste Electrode.

A novel electrochemical sensor for the sensitive and selective detection of methionine (Met) has been developed, utilizing copper (II)phthalocyanine (CuPc)-gold nanoparticles (AuNPs)– modified carbon paste electrode (CPE). This sensor was thoroughly characterized using a combination of techniques including cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry studies revealed a significant enhancement in the electrochemical behavior of methionine at the CuPc–AuNPs modified carbon paste electrode (CuPc-AuNPs/CPE) compared to both the unmodified carbon paste electrode and modified CuPc-CPE. The increase of the anodic redox signal for methionine was credited to a catalytic effect of AuNPs. This effect was examined using three different CPEs with varying concentrations of Au nanoparticles (0.03, 0.06, and 0.12 wt.%), while each electrode contained a fixed amount of CuPc (0.6 wt%). The sensor fabricated with 0.06% AuNPs exhibited superior sensitivity, as evidenced by differential pulse voltammetry analysis. This sensor exhibited an analytical range of 2.0 –150 µM and a limit of detection (LOD) of 0.5 µM. The developed sensor was successfully applied for the determination of methionine in pharmaceutical preparations.