DIFFERENTIAL PULSE POLAROGRAPHIC-DETERMINATION OF CEPHALOSPORINS AND THEIR DEGRADATION PRODUCTS

The differential pulse polarography (d.p.p.) of several cephalosporins - cephalothin, cephalosporin C, cephaloridine, cephalonium, cefuroxime, cephoxazole, cephalexin, cephradine, desacetylcephalosporin C, 7-aminocephalosporanic acid and 7-aminodesacetoxy-cephalosporanic acid - and some degradation products has been studied. Cephalexin, cephradine and 7-aminodesacetoxycephalosporanic acid, which contain an unsubstituted 3-methyl group but no reducible group, do not give d.p.p. peaks at the dropping mercury electrode, whereas certain of their degradation products do. The other cephalosporins, in which the 3-methyl group is substituted, give a d.p.p. peak at about-1 V (pH 2-4). Although these peaks are near the cathodic limit under the conditions used, these cephalosporins can be determined down to about 0.1 μg ml-1. Cephaloridine exhibits two d.p.p. peaks in this region, and can be determined. Cefuroxime, in addition to the peak at -IV, has a larger peak at -0.45 V (pH 2). Cephalonium shows a large well-defined peak at -0.72 V (pH 3) and two overlapping peaks. D.p.p. data for several degradation products including the diketopiperazines formed from cephalexin and cephradine are reported. © 1979.