Assessment of [F-18]fluoroethylflumazenil metabolites using high-performance liquid chromatography and tandem mass spectrometry

A simple procedure using HPLC and tandem mass spectrometry has been develop ed for the determination of fluoroethylflumazenil metabolites. Samples were precipitated with acetonitrile, evaporated to dryness followed by reconsti tution with methanol. As mobile phase, 50 mM ammonium formate-methanol (58: 42, v/v) was used. The method is valid both for cold and radiolabelled meta bolites. Various cold metabolites (hydroxylated and/or dealkylated) were id entified in rat and human microsome preparations. Radiolabelled metabolites arise from two or more transformations including hydroxylation. The method ology developed can be applied for further characterisation of metabolites, and for the determination of non metabolised [F-18]fluoroethylflumazenil i n routine clinical analysis. (C) 2001 Elsevier Science B.V. All rights rese rved.