High-performance liquid chromatographic analysis of a new β-lactam antibiotic, 6059-s (moxalactam)

Reversed-phase high-performance liquid chromatography was applied to the quantitative determination of a new β-lactam antibiotic, 6059-S, and its R- and S-epimers were resolved. The procedure was also applied to pharmaceuticals and human urine samples. Chromatographic separation was effected on a bonded hydrophobic stationary phase with two mobile phases: methanol-phosphate buffer for the resolution of the epimers and methanol-tetra-n-butylammonium phosphate for the quantitation of 6059-S. For the determination of 6059-S in human urine, the latter mobile phase was used successfully without interference by the other urine components. An in vivo experiment was conducted by administering intravenously 1 g of 6059-S to seven volunteers and analysing their urine by chromatographic and microbiological assays, and a comparison of the results gave a correlation coefficient of 0.9954. One-compartment model analysis of the time-course data revealed that 6059-S was excreted in urine intact with a rate constant of 0.433 h^-1.