In Silico predicted MS spectra - A good idea? October 14, 2016, 02:35:09 AM Dear,I noticed that as of recently most of the compounds currently in the METLIN online database are accompanied by CID MS spectra in positive ionization mode. At first I was delighted because this information proofed to be extremely helpful for me identifying certain metabolites. However, my mood rapidly changed when I found out that most of these newly added spectra where in silico predicted. My problem is that many of the in silico spectra are not indicated as such (e.g. Fig. 1), leaving me to think that they are based on actual empirical data (as was the case before). This caused me a great deal of confusion. Moreover, having seen many physical CID MS spectra, to me, all these predicted ones did not seem to have much to do with reality. I would like to know what program was used to make these spectra and how well this software preforms.In conclusion, if you decide to add in silico spectra please indicate this very clearly and explicitly state the software used. But in all honesty I do not think they are very helpful and are going to cause a lot of confusion. I would like to hear some other opinions on this matter.Regards,SebFig. 1) An in silico predicted spectrum which is not indicated as such.