A rapid and sensitive liquid-chromatographic method was developed to quantify the release of tobramycin from polymeric drug delivery systems in vitro. Pre-column derivatization of tobramycin and kanamycin B sulphate (internal standard) was carried out with 2,4,6-trinitrobenzenesulphonic acid. The sample volume required was only 50 μl. The chromatographic separation was achieved on an octyl reversed-phase column with UV detection at 340 nm. This isocratic method was performed at ambient temperature and required only 8 min of chromatography time. The standard curves were linear over the concentration range 0.50-50.0 mg l-1. Inter-day and intra-day relative standard deviations ranged from 3.6 to 9.3% and from 1.6 to 6.8%, respectively. The assay method was used to determine the tobramycin content in different pharmaceutical formulations and to study the stability of the drug both in the solid-state and in solution.
Bibliographical noteFunding Information:
Acknowledgements - The authors thank Drs R.J. Sawchuk, M.A. Hedaya, R.P. Remmel (College of Pharmacy, University of Minnesota) and E. Kwong (Merck Frosst, Canada) for their valuable suggestions. Financial support was provided by the Graduate School, University of Minnesota and by the Merck Sharp and Dohme Research Laboratories.
- pharmaceutical formulations
- pre-column derivatization
- reversed-phase liquid chromatography