Comparison of microbiological and high pressure liquid chromatographic assays of the new cephalosporin cefroxadine.

A method employing high pressure liquid chromatography has been developed for the new cephalosporin cefroxadine (CGP 9000). This uses Lichrosorb RP-8 5 micron as the stationary phase and 2 mM phosphoric acid mixed with methanol in the ratio 72:28 for the mobile phase. The retention time is 6.5 minutes. The procedure has a correlation with microbiological assay of r = 0.968 for sera after oral dosage and r = 0.944 after intravenous doses. Correlations in sera from each individual has ranged from 0.957 to 0.998. A protein binding of 5 per cent was found for a concentration of 10 microgram/ml and of 7.5 per cent at 2 microgram/ml. The HPLC method had a recovery of 92.5 at a low level of 2 microgram/ml and 95 per cent at 10 microgram/ml.