Institution: | aDepartamento de Química, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera 5700, San Luis, Argentina bDepartamento de Química, Universidad Nacional de Río Cuarto Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina |
Abstract: | Tyrosinase EC 1.14.18.1], immobilized on a rotating disk, catalyzed the oxidation of catechols to o-benzoquinone, whose back electrochemical reduction was detected on glassy carbon electrode surface at −150 mV versus Ag/AgCl/NaCl 3 M. Thus, when penicillamine (PA) was added to the solution, this thiol-containing compound participate in Michael type addition reactions with o-benzoquinone to form the corresponding thioquinone derivatives, decreasing the reduction current obtained proportionally to the increase of its concentration. This method could be used for sensitive determination of PA in drug and human synthetic serum samples. A linear range of 0.02–80 μM (r = 0.999) was obtained for amperometric determination of PA in buffered pH 7.0 solutions (0.1 M phosphate buffer). The biosensor has a reasonable reproducibility (R.S.D. < 4.0%) and a very stable amperometric response toward this compound (more than 1 month). |