Poly (4-Amino-3-Hydroxynaphthalene Sulfonic Acid)-Modified Glassy Carbon Electrode for Electrochemical Detection of Ephedrine in Human Urine

A polymer modified glassy carbon electrode was fabricated by electropolymerizing 4-amino-3-hydroxynaphthalene sulfonic acid (AHNSA) in a 0.1 M HNO3 and was characterized by cyclic voltammetry. The polymer modified electrode showed an excellent electrocatalytic activity towards the electrochemical oxidation of ephedrine. The oxidative peak current response of ephedrine at the polymer modified-glassy carbon electrode was found to show linear dependence on the concentration of ephedrine in the range of 8.0×10-6 to 1.0×10-3 mol L-1 with a linear regression equation, correlation coefficient and limit of detection (according to S/N=3; for n=4) of Ipa(?A)=0.971+0.042 C (?M), 0.99913 and 7.9×10-7 M, respectively. The proposed method was tested for the determination of ephedrine in human urine. Recoveries ranging between 92.06–93.15% for filtered and 81.15–86.30% for unfiltered human urine were achieved validating the developed method.