tag:blogger.com,1999:blog-3300702123878659843.post5446335455977732282..comments2024-03-26T05:25:50.831-04:00Comments on University of Ottawa NMR Facility Blog: The Consequence of Locking on the Wrong SolventGlenn Faceyhttp://www.blogger.com/profile/05146575170575279335noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-3300702123878659843.post-65124620841783284522013-01-23T09:32:24.571-05:002013-01-23T09:32:24.571-05:00The most interesting starts when you try to heat u...The most interesting starts when you try to heat up the sample. The D2O signal shifts about -0.1ppm/10°. As a result you will see in the spectrum the water line remaining at the same position, but all the rest lines shifting downfield. This in fact will still be convenient since the water line will be kept at the transmitter frequency for the suppression methods.<br /><br />VowaAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-25788206594644863822008-05-15T15:31:00.000-04:002008-05-15T15:31:00.000-04:00Dave,Its not just a problem with chemical shift re...Dave,<BR/>Its not just a problem with chemical shift referencing. Students are asked to declare a solvent so the spectrometer will "know" the correct field value to use to put the deuterium line of the solvent on-resonance. It is important for the deuterium line of the solvent to be on resonance for the automatic shimming to work well. In my view, the user is lucky to get anything at all if they declare the wrong solvent as often the spectrometer will not be able to "find" the lock signal at all and the sample will not be run in automation. Furthermore, even if the correct solvent is declared, the chemical shift reference should be checked and set manually by the user, as it is rarely at the desired precision. So.... no, its not too much to ask that the user reference the spectrum during processing (althogh I'm sure many do not) but it is very important to declare the correct solvent.<BR/><BR/>GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-26240723887908706562008-05-15T14:33:00.000-04:002008-05-15T14:33:00.000-04:00Is it too much to ask for users to set the chemica...Is it too much to ask for users to set the chemical shift reference themselves during processing? Or am I missing something...<BR/><BR/>DaveAnonymousnoreply@blogger.com