Monitoring in vitro experiments using microdialysis sampling on-line with mass spectrometry

A method has been developed for the real-time analysis of components in in vitro reactions by the on-line combination of microdialysis sampling (MD) with tandem mass spectrometry (MS/MS) and single stage mass spectrometry (MS). Apparatus and parameters associated with the integration have been studied. Analytical figures of merit for the drug gepirone have been determined. The qualitative 'limit of identification' was found to be 100 ng/ml and 200 ng/ml for methods using thermospray and electrospray MS interfaces, respectively. Using this approach, monitoring of in vitro experiments involving drug metabolites, enzymatic reactions, and ligand-protein binding interactions were performed.