1. Use of a Microplate Scintillation Counter as a Radioactivity Detector for Miniaturized Separation Techniques in Drug Metabolism
- Author
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Boernsen, K. Olaf, Floeckher, James M., and Bruin, Gerard J.M.
- Subjects
Drug metabolism -- Analysis ,Radioisotope scanning -- Methods ,Miniature electronic equipment -- Design and construction ,High performance liquid chromatography -- Usage ,Chemistry - Abstract
In miniaturized separation techniques, such as capillary electrophoresis (CE) or capillary liquid chromatography (LC), conventional on-line radioactivity detection of labeled compounds is restricted, because of insufficient sensitivity. It will be shown that a microplate scintillation counter for 96-well plates (TopCount) can be used as a sensitive and easy-to-handle radioactivity detector for capillary LC and CE. The attractive combination of capillary LC, eluent fractionation, and subsequent off-line counting is described. The new method is applied for rapid and sensitive separation and detection of (super 3)H-labeled parent drug and its metabolites at levels between 25 and 700 cpm in rat urine. The advantages of capillary LC coupled to the TopCount, and combined with LC-MS data, can be of benefit in many analytical areas, including the characterization of metabolites at low concentration within complex biological fluids. With the same setup, the fractionation with subsequent off-line counting is equally applicable to CE. This is demonstrated with electrophoretically separated (super 14)C-labeled impurities, nicely resolved from a negatively charged main compound, at low levels.
- Published
- 2000