Anionic surfactant reformed carbon composite voltammetric sensor for the efficient and sensitive detection of carmoisine in food samples.

Carmoisine (CM), an azo dye, imparts vibrant red color when added to the food, beverage, cosmetic and pharmaceutical products. The excessive intake of CM causes various health effects and hence it is essential to develop appropriate methods for the determination and quantification of CM in food samples. In this current work, a rapid detection and analysis of CM was performed via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques by harnessing sodium dodecyl sulfate modified composite sensor (SDSMCS). The morphological features and elemental composition of bare carbon nanotube graphite composite sensor (BCNGCS) and SDSMCS surfaces were compared and the difference between the working sensors was assessed. The active surface area was computed as 0.031 cm2 for BCNGCS and 0.049 cm2 for SDSMCS surfaces by employing CV technique. Key insights into the charge transfer process involved in the oxidation of CM was obtained by electrochemical impedance spectroscopy (EIS). The modified sensor demonstrated improved electrochemical features at optimal experimental conditions. The analysis validated that the electro oxidation of CM proceeds through adsorption-controlled kinetics at the surface of SDSMCS and exhibited a significantly low limit of detection (LOD) of 0.009 µM by CV and 0.073 µM by DPV technique, in the linear range of 0.1 µM to 1.1 µM and 0.1 µM to 0.9 µM, respectively. The attributes like reproducibility and repeatability of the developed SDSMCS were evaluated and the respective relative standard deviation (RSD) of 4.95% and 4.90% verified that the fabricated sensor is reliable for detecting CM in various commercial food samples with a recovery rate exceeding 97%. Surfactant- reformed carbon-based sensors provide a cost-effective and reliable platform that aligns with the evolving trends in field of electrochemical sensing.