Electrochemical Determination of Brilliant Blue and Tartrazine Based on an Ionic Liquid-Modified Expanded Graphite Paste Electrode

A sensitive electrochemical method was developed for the simultaneous determination of Brilliant Blue (BB) and tartrazine (Tz) using an ionic liquid-modified expanded graphite paste electrode (IL-EGPE). The IL-EGPE was prepared by mixing ionic liquid-expanded graphite composite (IL-EG) with solid paraffin. Compared with the EGPE, the IL-EGPE remarkably enhanced the electrocatalytic oxidation signals of BB and Tz. Under optimal experimental conditions, the designed IL-EGPE exhibited wide linear responses to BB and Tz ranging from 5.0 × 10–9 to 4.0 × 10–6 M and 1.0 × 10–8 to 1.0 × 10–6 M, respectively. The detection limits for BB and Tz were 2.0 × 10–9 M (1.6 ng/mL) and 3.3 × 10–9 M (1.8 ng/mL) at an S/N of 3, respectively. This electrode showed good reproducibility, stability, and reusability. The proposed method was successfully applied in the simultaneous determination of BB and Tz in a soft drink with satisfactory results.