Voltammetric determination of capsaicin using CeO<inf>2</inf>-surfactant/SWNT-modified electrode

Abstract

© 2017 King Saud University Glassy carbon electrodes (GCE) modified with carboxylated single-walled carbon nanotubes (SWNT-COOH) and CeO2-surfactants dispersions are developed for the capsaicin quantification. The effect of cationic cetylpyridinium bromide (CPB), anionic sodium dodecylsulfate (SDS) and nonionic Triton X100 as co-modifiers are tested. CeO2-CPB/SWNT-COOH/GCE provides 2.8- and 1.9-fold increase of capsaicin oxidation currents in comparison to bare GCE and SWNT-COOH/GCE, respectively, confirming the synergetic effect of the modifiers. Scanning electron microscopy (SEM) data confirm successful immobilization of the nanomaterials on the electrode surface leading to the significant changes in its morphology. The parameters of capsaicin electrooxidation are found. Differential pulse mode is applied for the capsaicin determination. The pulse parameters are optimized. The linear dynamic ranges of 0.10–7.5 and 7.5–500 μM of capsaicin with the limits of detection and quantification of 28 and 92 nM respectively confirm the high sensitivity of the method developed. The selectivity of the electrode toward capsaicinoids is proved. The method was applied for the total capsaicinoids quantification in real samples (red hot pepper spices and tinctures of Capsicum annuum L.). A good agreement with the UV-spectroscopic data is obtained.