Voltammetric analysis of capsaicin on reduced graphene oxide paste electrode in acidic medium

Author(s)

Lima, Guilherme Vieira ; Ribeiro, Maria Fernanda Muzetti ; de Azevedo, Larissa Silva ; de Faria, Juliene Morais ; de Oliveira, Marcelo Firmino

• Document type: Journal article
• Source: Microchemical Journal; v. 207, p. 9-pg., 2024-12-01.

Abstract

This article presents the application of a reduced graphene oxide paste electrode (rGOPE) for the electrochemical detection and quantification of capsaicin via cyclic voltammetry (CV) and square wave voltammetry (SWV) in an acidic medium. Using 50 mM Britton-Robinson buffer at pH 1.7 as the supporting electrolyte, the rGOPE demonstrated high sensitivity and a broad linear range for capsaicin quantification, with potential sweeps from-0.2 to +1.0 V (vs. Ag/AgCl) in CV and +0.3 to +1.0 V in SWV. The paste electrode, prepared by heating to 60 degrees C to promote paraffin agglomeration, demonstrated reliable electron transfer, with capsaicin undergoing irreversible oxidation to o-benzoquinone, which subsequently undergoes reversible transformation to catechol. SWV analysis at +0.67 V revealed a linear response from 1.43 to 11.35 mu M, with a determination coefficient of 0.993 (n = 3), sensitivity of 0.4971 mu A L mu mol-1, detection limit (LD) of 0.70 mu M, and quantification limit (LQ) of 2.32 mu M. Stability tests indicated that o-benzoquinone accumulation during successive scans diminished the capsaicin signal. The electrode demonstrated good repeatability (RSD = 13.31 %) and reproducibility (RSD = 19.24 %) across different solutions and days. Selectivity studies confirmed that ascorbic acid while producing a secondary signal, doesn't interfere after ethanol extraction due to its insolubility. Successful capsaicin recovery in authentic pepper samples further underscores the rGOPE's applicability. This study emphasizes rGOPE as a viable, efficient, and economical substitute for traditional chromatographic techniques in capsaicinoid detection, with potential applications in food safety and pharmaceutical evaluation. (AU)

• FAPESP's process: 22/12189-0 - Development of disposable voltammetric sensors for analysis of cannabinoids in samples of pharmaceutical interest
• Grantee: Marcelo Firmino de Oliveira
• Support Opportunities: Regular Research Grants