Electrocatalysis and sensitive determination of Sudan I at the single-walled carbon nanotubes and iron(III)-porphyrin modified glassy carbon electrodes

Iron-porphyrin (5,10,15,20-tetraphenyl-21H, 23H-porphine iron(III) chloride) was used in combination with single-wall carbon nanotubes (SWNTs) to modify a glassy carbon electrode (GCE). The electrochemical behavior of Sudan I on the iron-porphyrin-SWNT-DMF (N,N-dimethylformamide) modified GCE was studied by the cyclic voltammetry and square wave voltammetry. In pH 7.0 Tris–HCl buffers, Sudan I has a sensitive catalytic reduction peak at −0.08 V on the iron-porphyrin-SWNT-DMF modified GCE. Using square wave voltammetry, the linear relationship of Sudan I is 5.03 × 10−8 mol L−1–2.01 × 10−6 mol L −1 with the tropics equation: ΔiP = 3.40C + 3.43 × 10−6, and the detection limit is 1 × 10−8 mol L−1. And the iron-porphyrin-SWNT-DMF modified GCE was applied successfully in the determination of Sudan I in real samples.