Highly sensitive electrochemical sensor based on La3+-doped Co3O4 nanocubes for determination of sudan I content in food samples

•La3+ doped Co3O4 nanocubes as a nano-composite was synthesized.•It was used for modification of graphite screen-printed electrode.•The sensing method was used for determination of sudan I.•The method can be successfully applied for food sample analysis. In current research, a sensitive screen printed electrochemical sensor on the basis of La3+-doped Co3O4 nanocubes was fabricated to determine sudan I. The electrochemical performance of sudan I at this sensor was investigated in detail, presenting that this sensor had electrocatalytic behavior for oxidizing sudan I due to the significant peak current enhancement and the dropping of oxidation overpotential. Under the optimum conditions, the linear response range for sudan I concentrations by the modified sensor was 0.3–300.0 µM, and detection limit was 0.05 µM. Lastly, the suggested technique was also studied as a selective, easy, and exact electrochemical sensor to determine sudan I in food samples, including chili powder, tomato paste, and ketchup sauce.