Papaver alkaloids play a major role in medicine and pharmacy. In this study, [ring-13C6]-tyramine as a biogenetic precursor of these alkaloids was fed to Papaver somniferum seedlings. The alkaloid pattern was elucidated both by direct infusion high-resolution ESI-FTICR mass spectrometry and liquid chromatography/electrospray tandem mass spectrometry. Thus, based on this procedure, the structure of about 20 alkaloids displaying an incorporation of the labeled tyramine could be elucidated. These alkaloids belong to different classes, e.g. morphinan, benzylisoquinoline, protoberberine, benzo[c]phenanthridine, phthalide isoquinoline and protopine. The valuable information gained from the alkaloid profile demonstrates that the combination of these two spectrometric methods represents a powerful tool for evaluating biochemical pathways and facilitates the study of the flux of distant precursors into these natural products.