I offer my sincere thanks to all the respondents of my inquiry about the
ease of switching back and forth between BBO and CPMAS probes.
Many of you routinely switch between BBO and CPMAS probes and it can
take anywhere between 5-25 minutes depending on your skill level.
I have summarized the responses below as there were too many to include
them all. Also, I have included the response from Kelly Moran at Bruker
who anyone seeking a step-by-step guide to the Bruker probe switching
procedure should contact.
Response Summary:
The major theme in nearly all the responses was that the physical
switching of probes between BBO and CPMAS is not a complicated process
(unless perhaps you have a liquids autosampler that has to be positioned
away from its resting spot above the magnet in order to insert the
Standard Bore Solids Sample Transport tube). Almost everyone commented
on the longer experiment time required for solids work, and that it can
take much longer to switch back from solids to liquids depending on your
ability to realign the probe and restore the shims. Many of you also
cautioned me on the requisite switch from the high to low power
amplifier (actual cables and in edasp) on going from solids to liquids
to avoid frying the BBO probe. Finally, I was cautioned by many of you
to factor in all the accessories required for solids work (at least a
300W amplifier, fast ADC, MAS controller, high pressure dry air
capabilities)
A special thanks to Chris Hudalla at Waters Corporation who offered me
the option of driving up to his lab to observe the switch. I may take
you up on that if we decide to order one.
Thank you again. The response from Kelly Moran follows:
~~~~~~~~~~~~~~~~~~~~~
Russ Hopson, Ph.D.
NMR Facility Supervisor
Brown University
Department of Chemistry, Box H
Providence, RI 02912
(o) - 401-863-3069
(b) - 401-235-8306
Dear Russ,
Your email to AMMRL was forwarded to me.
I don't know with whom you spoke at Bruker about switching between
solids and liquids. I do the switching all the time and have written
two different step-by-step guides. There are two different guides
because the process depends on whether you have a standard bore (54 mm)
or wide bore (89 mm) magnet.
With a standard bore magnet, you switch the probes just as with any
other probe change (CPMAS probe is held in with 2 brass screws).
Additionally for the standard bore magnet, you slide a Standard Bore
Solids Sample Transport tube down through the top of the magnet. This
is a small-diameter, very light-weight aluminum tube that slides into
the top of the probe. The entire process, from one probe to another,
takes about 5 minutes (if you're not stopping at every step to read the
guide sheet).
With a modern wide bore magnet, in addition to changing the probe itself
and adding the Solids Sample Transport tube (for wide bore is a
fiberglass tube) you also have to change the BST-Bruker Sample Transport
tube. The BST a bright red tube and its collar is visible on top of the
magnet. This is a hollow tube made of heavy gauge aluminum. Changing
this tube in addition to the probe and solids transport tube adds a
little time to the process, but not much.
If you have an older wide bore magnet, you would not need to change the
red BST. Rather you'd have a different transport tube insert for your
liquids probes.
I'd be happy to send you the appropriate guide for your magnet bore
diameter.
With best regards,
Kelly
Kelly L. Moran, Ph. D.
Applications Scientist
Specializing in Solid State NMR
Bruker BioSpin Corporation
15 Fortune Drive
Billerica, MA 01821
978-667-9580 ext 5262
fax 978-667-2955
Applications Hotline
978-667-9580 ext 5444
Mon-Fri 9-5.30 Eastern Time
applab_at_bruker-biospin.com
Received on Mon Sep 13 2004 - 15:19:40 MST