Objective: The electrochemical analysis of ephedrine which is a sympathometric drug
has been studied using poly(Nile blue A) modified glassy carbon electrodes, cyclic voltammetry,
differential pulse voltammetry and square wave voltammetry.
Methods: The modified electrodes were prepared by potential cycling electropolymerization of
Nile blue A in 0.1 M phosphate buffer solution at pH 6.0. The redox behavior of ephedrine was
investigated in different buffer solutions at pH values between 5.5 and 9.0.
Results: Scan rate studies showed that the electron transfer reaction of ephedrine was diffusion
controlled. A linear response was obtained between the peak current and the ephedrine
concentration in the range of 0.6 to 100 μM with a limit of detection of 2.91×10-3 μM for
differential pulse voltammetry in Britton-Robinson buffer solution at pH 9.0. The linearity range of
ephedrine in human urine was between 1.0 and 100 μM with a detection limit of 8.16 nM.
Conclusion: The recovery studies in both pharmaceutical dosage forms and urine showed that the
proposed method ensured good selectivity, precision and accuracy without any interference from