Comparison of heterogeneous and homogeneous radioactivity flow detectors for simultaneous profiling and LC-MS/MS characterization of metabolites

Methods for simultaneous liquid chromatography-radioactivity monitor (LC-RA M) metabolite profiling and LC-tandem mass spectrometry (MS/MS) characteriz ation of metabolites are described. Profiling and characterization of metab olites from three drug candidates from different therapeutic areas were com pared using in-line heterogeneous LC-RAM-MS/MS and homogeneous LC-RAM-MS/MS methods. Although comparison shows that simultaneous metabolite profiling and characterization can be achieved using either heterogeneous or homogene ous-LC-RAM-MS/ MS systems, a homogeneous system has the advantage in the fo llowing aspects, (1) sensitivity; (2) ease of method transfer; (3) less pea k broadening problems due to the drug or metabolites adhering to the RAM ce ll; (4) accuracy in quantitation of the metabolites; and (5) the ability to load larger volumes of unprocessed biological fluids. Furthermore, the stu dy shows that some of the possible metabolites that do not ionize well with electrospray ionization (ESI) and eluded detection by heterogeneous-LC-RAM detection could be very easily detected and characterized using a homogene ous-LC-RAM-MS/MS system. (C) 2002 Elsevier Science B.V. All rights reserved .