A POLAROGRAPHIC STUDY OF THE REACTIVITY OF CEPHALOTHIN WITH ALKALINE PICRATE

摘要

A polarographic study was undertaken to investigate the reaction between alkaline picrate (AP) and the antibiotic cephalothin (C) at 25.0 +/- 0.1 degrees C in 0.25 mol/liter NaOH. Under the reaction conditions employed, a single polarographic reduction wave at -1.67 V was observed for an alkaline cephalothin blank. Three other polarography waves were also observed at different times of incubation, with half-wave potentials (E(1/2)) vs SCE of -0.29, approximately -0.4, and -0.75 V. The wave at -0.75 V was attributed to the formation of sulfide. For an alkaline picrate blank, four reduction waves were observed, with E(1/2)'s of -0.62, -0.78, -0.93, and -1.36 V. For C:AP test solutions containing a 1:1 molar ratio, waves 2 and 3 of AP formed a composite wave within 1.5 min of reaction, with an apparent E(1/2) of -0.90 V. After 60 min of reaction, the AP diffusion currents (I-d) for waves 1, composite, and 4 decreased, respectively, by 12, 14, and 22%. After 10 min HCl treatment and subsequent restoration of alkalinity, I-d's for waves 1 and composite further decreased by 23 and 37%, whereas the I-d for wave 4 increased by 86%. For the TLC studies, a picramate spot was observed for a 1:1 C:AP reaction incubated for 1 h at 50 degrees C in 0.25 mol/liter NaOH, but was not observed for the same solution incubated at 25 degrees C for 2 h. The present studies verify the reactivity of cephalothin with alkaline picrate and reveal a rapid reaction mechanism, with the involvement of the nitro groups of alkaline picrate. (C) 1996 Academic Press, Inc. [References: 49]