Polyethylenimine-carbon nanotubes composite as an electrochemical sensing platform for sensitive and selective detection of toxic rhodamine B in soft drinks and chilli-containing products

• A novel sensor for stable determination of rhodamine B has been presented. • Highly selective, repeatable and reliable reproducible sensor obtained. • A good linear concentration range (0.01 − 10 μM) and a low LOD (6.0 nM). • The developed sensor can be applied in rhodamine B detection in actual sample. Rhodamine B (RhB) is a toxic and carcinogenic additive that was once overused in foodstuffs. Its quick detection and monitoring are vital to human health and various food chains. Hereby for the first time, the polyethylenimine and multi-walled carbon nanotubes composite modified glassy carbon electrode (MWCNTs-PEI/GCE) was employed to determine RhB. The MWCNTs-PEI was prepared by sonicating the mixture of MWCNTs and PEI solution and characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV). Compared with single material modified electrodes, the electrochemical response of RhB was enhanced at the MWCNTs-PEI/GCE because of the synergistic effect of the composite. To improve the sensitivity of the determination, the experimental conditions were optimized, and the calibration curve of quantitative determination was obtained by second-order derivative linear scan voltammetry (SDLSV). Under the optimum conditions, the proposed method showed a good linear range (0.01−10 μM) and a low detection limit (6.0 nM), and the method can be employed to determine RhB in food samples.