Hi Ken,
If this turns out to not be an isolated incident, you may want to clean the
top of your shim stack, both the beveled part on top where the spinner rests
and an inch or so below that the lower part of the spinner inserts into.
Dirt in these areas can cause spinning issues, prevent the sample from
inserting all the way (leading to lock/shim failures) and prevent the sample
from ejecting reliably. I started having these issues on two systems earlier
this year and in both cases cleaning the shim stack (water/isopropanol) fixed
the issue. In my case it was a matter of removing the probe, removing the
autosampler to access/loosen the three long screws that hold the BST and
shim stack together, then loosening the clamp under the magnet that holds
onto the shims.
Alex
Alex Greenwood (he/him)
Manager, NMR Facility
University of Cincinnati
123C Crosley Hall
Office: 513-556-9211; Cell: 412-952-8044
https://www.artsci.uc.edu/natural-sciences/chemistry/core-facilities/nuclear-magnetic-resonance-facility.html
> From: main_at_ammrl.groups.io Behalf Of Steve Clemens via groups.io
> Sent: Tuesday, August 12, 2025 11:03 AM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Stuck sample is BST with SampleMail in the way
Ken,
Depending on how the sample is "stuck", you might not need to do any of this.
I have had a situation where a sample was in the bore but was binding against
something and wouldn't come up. With the lift gas on, I lowered a stick down
(with a small ball of kimwipe on the end) just to 'touch' the top of the
sample, at which point it righted itself and came up.
I suggest this as a really easy way to deal with the issue.
Also, if I understand the situation correctly, I personally would be very wary
of removing the BST with the probe still mounted. The bottom part of the BST
(where it mates to the shim stack/turbine) is the same diameter as the outside
of the upper part of the spinner, so this could only help if the sticking is
between the BST and the outer part of the spinner (ie. where the reflective
tape is). Otherwise you will pull the BST up and the sample will still be
sitting on top of the shim stack/turbine part, in which case you'll need to
drop your probe (and remove the shim stack) to get that out anyway.
Also, if it is stuck on the side of the BST, there is a risk of it coming loose
as you pull the BST up, and then you'll be cleaning up a mess (as it will fall
back down the bore and almost certainly break the tube).
Steve
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Received on Tue Aug 12 2025 - 09:18:09 MST