Hi Chuck,
It is our experience here in Bruker U.K. that is better
to have a minimum of 70KHz between two spectrometers to avoid
these problems. This is approximately the total field available on a BSMS
Z0 range. This of course depends where your current field value is at the
moment with regards to the BSMS field value. If necessary you may have to
shift the frequency on both instruments.
The procedure is quite simple. To see how much range you have you can measure
a water peak at the current value on resonance and then adjust the field on
the BSMS and then re-measure the water peak and measure the distance moved
(do this unlocked with the field sweep off).
>From there you can decide which way you which to move the basic frequency.
For this do a CF and change the basic frequency to the one required from your
previous test. This will generate a new absolute lock frequency relative to
the new basic 1H frequency. It is important when you do the CF to update the
nuclei table with the restore button for the new basic frequencies for all
nuclei.
Once this is done you need to adjust the BSMS field position by searching for
the lock resonance (making sure that you have the correct solvent for the correct
lock shift in the BSMS and then update the new field value in the BSMS table.
Once done you will need to do an expinstall to update the standard parameter sets.
Remember any of your own old data sets if read in will contain the old frequencies
so remember to update these if you intend to use these.
Good luck and best wishes,
Adrian Bryant
-----Original Message-----
From: D. Chuck Dunbar [mailto:ddunbar@olemiss.edu]
Sent: 27 February 2005 23:29
To: BUM
Subject: NMR cross talk
Dear Bums,
We have two 400 MHz instruments which are interfering with each other.
Our primary problem is when the AV400 is decoupling 13C during an HMQC
we get strong noise spikes in a 13C running on the other instrument. .
The current frequencies are 400.13 and 400.17 MHz. We are thinking of
trying to change the fields further apart but we are not sure if this
will fix the problem. I would like to get others opinion on this.
A second related question is how much can you change the field
using the Z0 coil and how would you do this in the software? Our other
option is to move one of the instruments but this would not be easy.
Any insight into this matter will be appreciated.
Thanks, Chuck
-- D. Chuck Dunbar, Ph.D. Associate Research Scientist Thad Cochran Research Center National Center for Natural Products Research University, MS 38677Office (662)915-1025 Lab (662)915-1021 Fax (662)915-7989
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