i like this post (click again to cancel)
1
i dont like this post (click again to cancel) remove favorite mark from this question (click again to restore mark)

We try to setup a used Bruker Avance 200 system. After frequency search we started to setup lock and shim file. Using D2O everithing worked quite well - the spectrometer find the lock and shimming leads to a 1H linewitdth less than 3Hz (10mm tube). Next step we wanted to set the files for acetone-d6. The system finds the lock, but now we see two well shaped lines separated by 0.48 ppm. Shimming does not solve this problem. We also tried acetone-d6 from a different bottle but still see two signals.

Thanks for your comments

asked Nov 17 '10 at 05:47

Thomas%20Tr's gravatar image

Thomas Tr
11

is it 0.48ppm away? Water should be at 2.8 and acetone 2.05 - Magnethead (Nov 19 '10 at 12:16)

Thomas, you can post a spectrum, btw. Just edit the question and hit the "image" button and insert a cropped image of "Print Screen" result. Probably the "Print Screen" button works on your keyboard.. - Evgeny Fadeev (Nov 19 '10 at 12:23)


2 Answers:
i like this answer (click again to cancel)
1
i dont like this answer (click again to cancel)

Hi - you may be seeing the residual acetone-d5 (7 close spaced lines in a multiplet) and H2O (your unexpected peak). Try adding a very small additional amount of H2O and see if the non-coupled resonance increases in intensity. Most solvents contain water, sometimes you can make out two resaonances for "water" - H2O and HOD. Good luck

Andy

link

answered Nov 19 '10 at 00:01

Andy%20Edwards's gravatar image

Andy Edwards
11

i like this answer (click again to cancel)
0
i dont like this answer (click again to cancel)

Maybe it's just shimming problem, did you try 5 mM tube and spin the sample? Are X and Y shims optimized?

Was your magnet recently energized or shim files are brand new?

link

answered Nov 19 '10 at 12:17

Magnethead's gravatar image

Magnethead
42

updated Nov 19 '10 at 12:18

Your answer
Please start posting your answer anonymously - your answer will be saved within the current session and published after you log in or create a new account. Please try to give a good answer, for discussions, please use comments and please do remember to vote (login to vote)
toggle preview

powered by CNPROG