1.) As feedback from my previous question about “WATER” in automation please read appended e-mail response containing description for a simple fix.
2.) Can anyone help me with the following? I desire to measure T1 of solutes in water (not D2O). Our spectrometer is an Avance 300, Microbay, and our probe is a broadband probe.
In an attempted to suppress the overwhelming water signal I incorporated selective pulses into the inversion recovery sequence (soft -180 pulse on water before hard +180; and soft -90 before +90).
This approach seems to work fine for samples in D2O with residual water but for H2O samples I seem to run into additional problems I suspect to be due to rf pulse inhomogeneity. This suspicion is because upon inspection of the spectrum from a single hard 270 degree pulse applied on a H2O sample I noticed that the resonance is distorted. Instead of an inverted Gaussian signal the shape of the resonance looks more like a w (double u).
Since this distortion only shows for strong signals, my first thought was that I am perhaps dealing with effects of radiation damping, the B-field created by the sample itself in response to the rf pulse. On the other hand I don’t understand how rf-field homogeneity and radiation damping would be connected.
Any helpful comments that explain what I am observing, and any helpful comments how I might deal with the problem would be greatly appreciated.
Hi Markus,
the fix is easy, follow the steps below
rpar WATER all
click on the Procpar tab
change F1P [ppm] = 100
change F2P [ppm] = -100
wpar WATER all
this will be fixed in TopSpin 2.0
Greetings,
Peter
From: mhoffman@brockport.edu (by way of BUM <bruker-users-mail@purcell.cchem.berkeley.edu>)
Subject: gradient shimming in automation
Date sent: Mon, 15 May 2006 07:35:16 -0700
To: BUM <bruker-users-mail@purcell.cchem.berkeley.edu>
Send reply to: mhoffman@brockport.edu
> Hi all,
>
> I meant to introduce myself for quite some time. My name is Markus Hoffmann
> and I am teaching Physical Chemistry at SUNY Brockport a four-year liberal
> arts college. After three NSF proposal attempts we finally received funding
> and subsequently purchased an Avance 300 with 24 autosamper, VT and
> gradient capabilities, which is now installed for about a year.
>
> I thought a nice way of writing a first message is to provide some info that
> might be useful for others too:
>
> For Analytical Chemistry (~40-50) students we were in the process of
> implementing a new experiment to analyze the amount of 2-propanol and ethyl
> acetate in comercial nailpolish remover ("Pretty Nails") using the standard
> addition method. Since there would be a fair amount of sample preparation
> involving aqueous solutions, we we thought it to be desirable were to run
> not use deuterated solvents and run the samples through automation using
> gradient shimming, which is fine as long as solute concentration is less
> than at least 20 volume%.
> However, automation would hang up and eventually I noticed that in
> automation gradient shimming would attempt to turn on the lock even though
> settings for the automation run were set to "lock off". I asked how to
> solve this problem just about any of the Bruker personnel who I met during
> the user training sessions. Finally, during the second week of training I
> received the correct hint. The lock really stays off in automation only
> when the experiment setting (Proton) and the gradshim1D1h file have the
> lock setting set to "lock off".
> Thus, one needs to make the changes in these two files, save the proton
> experiment as another name, load that one into Icon NMR and make it
> accessible to the user who would like to use this experiment. We got very
> nice spectra with gradient shimming in automation!
>
> Finally, a question, does anyone no what the status is on the "water" water
> suppression experiment in automation. Is there a fix out there by now?
>
> Markus
>
>
> --
>
> __________________________________________________________________________
>
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