Determination of cefsulodin in biological fluids by high-pressure liquid chromatography

Cefsulodin is a third-generation cephalosporin with a unique specificity for Pseudomonas aeruginosa. To study the pharmacokinetics of this agent in children, a rapid and sensitive high-performance liquid chromatographic micromethod was developed for plasma and urine. Protein was precipitated from plasma with one volume of cold methanol, and 20 microliter of the resulting supernatant solution was injected into a Zorbax C-8 reversed-phase column. The mobile phase was composed of 4.5 parts acetonitrile and 95.5 parts of 0.035 M ammonium acetate buffer (pH 5.2). Flow rate was 1.0 ml/min and peaks were detected at 265 nm. A flow gradient from 0.3 to 2.0 ml/min over 34 min was employed for urine. The analysis had a limit of detectability of 1 microgram/ml and a between-day coefficient of variation of 4.4 and 5.0 for 100 and 10 micrograms/ml samples, respectively.