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I'm trying to measure T1 for a compund at 1mM in water using t1ir. Seeing how my concentration is so low, phasing my compound's peaks comes at a great price and so the value of T1 I obtain seems wrong.

I get T1 =1.275s and I calculated my d1= 5xT1 -AQ = 5x1.275 - 5.4525= 0.9225

When I increase the d1 in a watergate 1H acquisition, the intensity of my peeks increases until d1=10s.

Does anyone have an explanation or tips for measuring T1 in water?

asked Sep 19 '14 at 02:30

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updated Sep 19 '14 at 02:31

Did you check the PW90 before? This has to be done, because there is a very precise 180 pulse needed. - Ulrich Haunz (Sep 22 '14 at 06:14)

How did you set table for time delays for t1ir ? And one more thing, why do you use so long AQ ? I can bet that after 2s of aqusition you are harvesting only noises. One more thing, which version of TopSpin are you using to do the calculations ? - Arkadiusz Leniak (Sep 23 '14 at 01:16)

Yes I calibrated p1 (pw90). For time delays I used a list 0.001 0.050 0.100 0.200 0.300 0.500 0.800 1 1.5 2 2.5 3 3.5 4 4.5 5 AQ is related to the fid size, I use a 64k point fid (what would you use?). I have also been told to take AQ as 3 to 5 times the fid. I am using topspin 3.2 - gravatar (Oct 22 '14 at 03:43)

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Hello gravatar,

keep the d1 constant to 5*T1 = 6.4 s ... not .9 or 1 second! Take more time for the relaxation, ... if it is too short, it makes nasty things!

What is the T1 of the water signal?

also you can use SI = 3 to 4 * TD for smoothing the peaks.

Your delay list is OK, ... better is if you end up differently, 1 2 5 10 20 seconds - think logarithmic not linear.

try instead of TopSpin also the new dynamic center from Bruker ... for t1 and kinetics you can take your TopSpin license! And have a closer look into the Workshop/Manuals of "dynamic center". This is free downloadable from the Bruker-Biospin Service pages, if you are a registered user. Registration is only your postal and e-Mail address.



answered Oct 23 '14 at 08:35

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Ulrich Haunz

another hint: TDEFF ... look how long the FID is in TD data points. These are the effective datapoints. TDEFF sets the following noise data points to zero - zerofilling without noise. LB makes the signals too broad! - Ulrich Haunz (Oct 23 '14 at 08:37)

http://www.theresonance.com/2014/categories/structural-biology/dynamics-center-kinetics-tool-video-tutorial-series - Ulrich Haunz (Oct 23 '14 at 08:39)

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