DIFFERENTIAL PULSE ADSORPTIVE STRIPPING VOLTAMMETRY DETERMINATION OF EPINEPHRINE WITH β-MERCAPTOETHANOL SELF-ASSEMBLED MONOLAYERS MODIFIED ELECTRODE

ABSTRACT

β-Mercaptoethanol self-assembled monolayer modified electrode (ME/Au SAMs) has been fabricated on bare gold. ATR-FTIR was used for the characterization and surface structure of the films. The films, as mediator, accelerated the electron transfer and showed an excellent electrocatalytic activity for the oxidation of the EP. The electrochemical behavior of epinephrine at ME/Au SAMs has been studied by cyclic voltammetry. The electrocatalytic mechanism has been explored. At potential of −0.044 V (vs SCE) in pH 4.0 aqueous buffer, a first oxidation wave is observed for epinephrine at the modified electrode (electrochemical oxidation of leucoepinephrine to epinechrome). In contrast, the first oxidation wave is not observed for norepinephrine or dopamine at the same condition. Under the conditions chosen, the modified electrode provides a linear response for epinephrine in the concentration range from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol/L by differential pulse adsorptive stripping voltammetry. The detection limit (three times the signal blank/slope) was 3.3 × 10⁻⁸ mol/L. The modified electrode could eliminate the interference of norepinephrine, dopamine, and glucose at 10-, 40- and 1000-fold concentration of epinephrine (at 8.0 × 10⁻⁶ mol/L), and it has been satisfactorily used for the determination of epinephrine in injection.

Keywords:

• β-mercaptoethanol
• Self-assembled monolayers
• Epinephrine
• Differential pulse adsorptive stripping voltammetry

ACKNOWLEDGMENTS

The work was supported by Natural Science Foundation of Hubei province of P. R. China (2000J007).