I was recently speaking to a number of very experienced (certainly compared to me anyhow) practitioners in metabolite identification. They were from 4 different pharmas but they all basically gave the same response. Their goal is to rapidly identify "active" metabolites and they all seemed to use basically the same approach. My argument was they were barking up the wrong tree as they could not guarantee that their strategies would pick up either all of the actives or indeed any. I suggested a better approach was to be able to at least identify all of the metabolites produced and then to use this as a starting point for further work in identifying any "actives". My feeling being that at least they wouldnt miss anything with this approach. Unfortunately it was neither the time nor the place for a heated debate but I would very much like to hear the opinions of the members of the forum.