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 aqueo us solutions of pH ranging from 1 to 10 was investigated. The reactant is strongly adsorbed in acidic media, while in neutral and alkaline s olution, electrode reaction is not affected by adsorption phenomena. A kinetic study of the methoxyimino group elearoreduction to methanol a nd an aminic derivative in acidic media was carried out. The overall e lectrode process is controlled by a heterogeneous protonation step pre ceded by a fast electronation step in the pH range 1 to 3, where as fo r 3 < pH < 5, the rate determining step (rds) is the first electronati on step. Moreover, a fast protonation precedes the rds in the whole ac idic medium. The best experimental conditions for the detection of CFX M in differential pulse polarography (DPP) were found. Owing to its hi gh adsorptivity, CFXM is detectable at a concentration as low as 1 x 1 0(-8) M at a pH of about 2.