Electrochemical Analysis of Fast Sulphon Black F Using Poly(L-Tyrosine)-Modified Carbon Paste Electrode

An electrochemical approach has been employed for the selective and sensitive determination of fast sulphon black F (FSB-F) using an electrochemically polymerized L-tyrosine (L-TN)-modified carbon paste electrode (L-TNMCPE). This modified electrode exhibits an effective irreversible oxidation peak at a potential of 0.6180 V, with a current sensitivity of 17.88 µA in 0.2 M phosphate-buffered saline (PBS) at pH 6.5, indicating its ability to clearly detect the oxidation of FSB-F. The characterization of the L-TNMCPE and the bare carbon paste electrode (BCPE) was observed using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The developed sensor presents a favorable approach for simultaneously detecting FSB-F and indigo carmine (IC), while also investigating potential interference from various metals and organic compounds. Scan rate results indicate that the reaction is absorption-controlled. Additionally, various experimental aspects are examined, including the pH and concentration variation. The modified electrode exhibits remarkable electrochemical behavior with a limit of detection (LOD) of 0.75 × 10⁻⁶ M and a limit of quantification (LOQ) of 2.5 × 10⁶ M. The L-tyrosine (L-TN)-modified carbon paste electrode shows good reproducibility, repeatability, and stability.