REDOX LABELING OF 2 ANTIEPILEPTIC DRUGS WITH METALLOCENES AND THEIR SIMULTANEOUS DETECTION BY A NAFION-MODIFIED ELECTRODE

Two different cationic redox labels, i.e. a ferroceneammonium ion and a cobaltocenium ion, mere covalently attached to two anti-epileptics, phenytoin and phenobarbital, respectively, The two labeled drugs posse ss distinct standard redox potentials of 0.39 V for the phenytoin deri vative and -0.92 V for phenobarbital derivative (vs Ag/AgCl, Cl- 0.05 M) at a carbon paste electrode, After preconcentration in a polyanioni c Nafion-loaded carbon paste electrode the positively charged labeled phenytoin and phenobarbital derivatives could be simultaneously detect ed in concentration ranges which were relevant to the therapeutic rang es of the antiepileptics, with a view to a future dual-analyte immunoa ssay, Square-wave voltammetry permitted detection limits of 5 x 10(-8) M (for the phenytoin derivative) and 2.5 x 10-(8) M (for the phenobar bital derivative) for non-simultaneous detection. (C) 1998 John Whey & Sons, Ltd.