Multi-wall carbon nanotube film-based electrochemical sensor for rapid detection of Ponceau 4R and Allura Red

The monitoring of synthetic colourants in foods is very important due to their potential toxicity and pathogenicity. Herein, an electrochemical sensor for rapid and simple detection of Ponceau 4R and Allura Red was constructed using multi-wall carbon nanotube (MWNT) sensing film. In pH 7.0 phosphate buffer, two oxidation peaks are observed at 0.56 and 0.68 V for Ponceau 4R and Allura Red. Because of its large surface area and high accumulation efficiency, the MWNT film sensor remarkably enhances the oxidation signals of Ponceau 4R and Allura Red. The detection parameters such as pH value, amount of MWNT, accumulation potential and time were optimised. The MWNT film sensor possesses high sensitivity to Ponceau 4R and Allura Red, and the limits of detection are as low as 15 and 25 μg L−1. Finally, the MWNT sensor was successfully used to detect Ponceau 4R and Allura Red in different soft drinks.