A sensitized chemiluminescence system based on the reaction between Ni(IV) complex and luminol: applications to the determinations of beta(2)-agonist drugs

摘要

A new, simple but efficient chemiluminescence system has been developed for determination of two beta(2)-agonist drugs, ractopamine and fenoterol. The system is based on the chemiluminescence reaction of a Ni(IV) complex with luminol in alkaline media, while ractopamine or fenoterol can dramatically enhance chemiluminescence intensities. Under optimum conditions, chemiluminescence intensities are proportional to the concentrations of the drugs in the ranges of 1.0 x 10(-8)-1.0 x 10(-6) mol dm(-3) for ractopamine and of 1.0 x 10(-9)-1.0 x 10(-7) mol dm(-3) for fenoterol, respectively. The limits of detection (3 sigma) are 1.0 x 10(-10) mol dm(-3) for ractopamine and 1.0 x 10(-11) mol dm(-3) for fenoterol. Based on the kinetic characteristics of the chemiluminescence reaction, the chemiluminescence spectral change and free radical trapping experiment, a chemiluminescence reaction mechanism is proposed which involves free radicals in the Ni(IV)-luminol-ractopamine/fenoterol chemiluminescence systems. The mechanism of chemiluminescence enhancements by ractopamine/fenoterol to the Ni(IV)-luminol detection system is discussed.