The electrochemical properties of dopamine, epinephrine and their simultaneous determination at a poly(L-methionine) modified electrode

A poly(L-methionine) modified electrode, fabricated by electrochemical immobilization of the L-methionine on a glassy carbon electrode, was used for simultaneous determination of dopamine and epinephrine through cyclic voltammetry. The electrochemical properties of dopamine and epinephrine have been investigated. This sensor gave two separated cathodic peaks at −0.282 and 0.112 V for EP and DA, respectively. A linear response was obtained in the range of 5.0 × 10 −7 to 1.0 × 10 −4 mol l −1 for epinephrine, and 1.0 × 10 −6 to 5.0 × 10 −4 mol l −1 for dopamine. The detection limits were 3.6 × 10 −7 mol l −1 and 4.2 × 10 −7 mol l −1 for epinephrine and dopamine, respectively. This method was successfully applied for simultaneous determination of dopamine and epinephrine in human urines.