Sensitive voltammetric determination of Sudan I in food samples by using gemini surfactant–ionic liquid–multiwalled carbon nanotube composite film modified glassy carbon electrodes

A novel modified electrode was fabricated, which comprised of hydrophobic ionic liquid (i.e. trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, [P6,6,6,14][NTf2]), multiwalled carbon nanotubes (MWNTs) and cationic genimi surfactant (i.e. C12H25N(CH3)2–C4H8–N(CH3)2C12H25Br2, C12–C4–C12). Cyclic voltammetry and linear sweep voltammetry were used to investigate the electrochemical behaviour of Sudan І. The components showed good synergic interaction in sensing Sudan І, thus the modified electrode presented higher sensitivity. After optimising the experimental conditions, the anodic peak current of Sudan I was linear to its concentration in the range of 0.05–2 μmol l−1, and the detection limit was 0.03 μmol l−1 in pH 4.5 potassium biphthalate buffer with acetonitrile. The modified electrode had good stability and repeatability. It was applied to the detection of Sudan І in hot chilli powder and ketchup samples, and the recovery was acceptable.