Poly(2-mercaptobenzothiazole) modified electrode for the simultaneous determinations of dopamine, uric acid and nitrite

Poly(2-mercaptobenzothiazole) (PMBT) modified glassy carbon electrode (PMBT/GCE) has been fabricated and employed for the selective and simultaneous determinations of dopamine (DA), uric acid (UA) and nitrite (NO2−) in 0.1 mol L−1 phosphate buffer solution (PBS, pH 6.0). The PMBT modified GCE not only exhibits electro-catalytic effects toward the electrochemical oxidations of DA, UA and NO2− with negatively shifted oxidation potentials and enhanced peak current responses, but also resolves the weak and overlapped voltammetric responses of DA, UA and NO2− into three strong and well-defined oxidation peaks using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques, which can be applied for the selective and simultaneous determinations of DA, UA and NO2− in their mixture. The surface morphology of PMBT film has been investigated by using scanning electron microscope (SEM). The SEM image shows the formation of continuous PMBT film composed of nano-scaled particulates with the diameter varying in the range of 15-25 nm. Under the optimum conditions, the linear concentration dependences of DPV peak current responses are observed for DA, UA and NO2− in the concentration ranges of 0.8-45 μmol L−1, 1.0-165 μmol L−1 and 60-1000 μmol L−1, with the correlation coefficients of 0.9996, 0.9994 and 0.9979, respectively. The detection limits (S/N = 3) are 0.05 μmol L−1, 0.10 μmol L−1 and 0.30 μmol L−1 for measuring DA, UA and NO2−, respectively. The modified electrode has been used for simultaneous determinations of DA, UA and NO2− in human urine and serum samples using standard adding method with satisfactory results.