We acquired MR spectroscopy signals from phantoms with certain metabolites in our Lab(at 37 centigrade), using a Bruker 9.4T MR machine. We compared the peaks of metabolite with the literature[In Vivo NMR Spectroscopy, de Graaf], and they are not the same. The differences are in the range of 0 to 5 Hz.
We reacquired signals with different temperatures and with a calibrated pH meter. Shifts change more or less linearly with temperature but are different from the literature.
I was wondering if any Lab did the same measurement? I could not found a study with phantom measurement in 9.4T.
I attached a picture illustrating the issue in the Cr+NAA phantom.
David Stephenson Agreed, I was thinking if shifts are inevitable, so the linear combination of basis set will fail in higher field
Come on, just 5Hz! ??? Ok, probably you do not have the proper sensitivity to this. Chemical shifts depend on (a) temperature, (b) pH, (c) ionic force, (d) concentration, (e) solvent type, as a minimum. ALL these fators can cotribute to variations of up (sometimes over) 0.1 ppm. What you have found is almost incredible for how well it matches, not for the differences!
Btw, I see you work at CAS Inst. of Sci.Instruments Instruments in Brno. Please, give my greetings to Zenon, the son of a water fighter (just tell him, he will understand :-) ).
Stan Sykora thanks for your answer. I would add hardware imperfections as well. Apparently, we have to live with this. I definitely bring your greetings, I bet he will understand :))
- Badges
- Science topic
- Similar topics
- Methodology
- Laboratory