A novel electroanalytical assay for sulfamethazine determination in food samples based on conducting polymer nanocomposite-modified electrodes

The toxicity of sulfa drugs has attracted great attention, and the reported electrochemical methods for sulfa drugs usually employ a high oxidation potential. In this work, a one-pot synthesized conducting polymer nanocomposite containing poly(3,4-ethylenedioxythiophene) (PEDOT) and MnO2 was cast on a screen-printed carbon electrode (SPCE), and the modified electrode showed superior electrochemical activity over a bare electrode for sulfamethazine (SMZ) determination. The SMZ detection was based on the electrochemical oxidation product, which showed an adsorptive property and exhibited a redox couple at 0.39 V in pH 3 phosphate buffer solutions (PBS). The electrode surfaces were well characterized by the water contact angle technique, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and cyclic voltammetry. By the use of square wave voltammetry (SWV), a wide linear response to SMZ, from 1.0 mu M to 500 mu M, was obtained. The sensitivity and detection limits (S/N = 3) were 0.115 mu A mu M-1 and 0.16 mu M, respectively. The proposed method and a reference high-performance liquid chromatographic method (HPLC) were applied for the determination of SMZ in two real samples using the standard addition method, and satisfactory recoveries and good agreement were obtained.