POLAROGRAPHIC-BEHAVIOR OF THE BETA-LACTAM ANTIBIOTIC CEFUROXIME AND STUDY OF THE REDUCTION-MECHANISM IN ACIDIC MEDIA

Polarographic behavior of the cephalosporin Cefuroxime (CFXM) in aqueous solutions of pH ranging from 1 to 10 was investigated. The reactant is strongly adsorbed in acidic media, while in neutral and alkaline solution, electrode reaction is not affected by adsorption phenomena. A kinetic study of the methoxyimino group elearoreduction to methanol and an aminic derivative in acidic media was carried out. The overall electrode process is controlled by a heterogeneous protonation step preceded by a fast electronation step in the pH range 1 to 3, where as for 3 < pH < 5, the rate determining step (rds) is the first electronation step. Moreover, a fast protonation precedes the rds in the whole acidic medium. The best experimental conditions for the detection of CFXM in differential pulse polarography (DPP) were found. Owing to its high adsorptivity, CFXM is detectable at a concentration as low as 1 x 10(-8) M at a pH of about 2.