Simultaneous determination of Ponceau-4R and Allura Red in soft drinks based on the ionic liquid modified expanded graphite paste electrode

A convenient and sensitive method was developed for the simultaneous determination of Ponceau-4R and Allura Red using an ionic liquid modified expanded graphite paste electrode (IL-EGPE). The IL-EGPE was prepared by mixing ionic liquid-expanded graphite (IL-EG) composites with solid paraffin. Based on the advantageous functions of IL and EG, IL-EGPE showed enhanced electrocatalytic activity towards the simultaneous oxidation of Ponceau-4R and Allura Red. Under optimal experimental conditions, the IL-EGPE exhibited wide linear responses to Ponceau-4R and Allura Red ranging from 6.0 to 7.5 mg L−1 and 5.0 to 0.5 mg L−1, respectively. The detection limits for Ponceau-4R and Allura Red were 1.15 and 0.89 μg L−1 at a signal-to-noise ratio of 3, respectively. The designed electrode showed good reproducibility, stability and reusability. The proposed method was successfully applied in the simultaneous determination of Ponceau-4R and Allura Red in soft drinks. This method presented a simple, rapid and sensitive platform for simultaneous determination of Ponceau-4R and Allura Red and would become a versatile and powerful tool for food safety.