probe insert scratches, NMR-tube labels
G. Pearson (gpearson@blue.weeg.uiowa.edu)
Wed, 24 Apr 1996 11:46:48 -0500
Hi, Jim.
SCRATCHES ON GLASS INSERTS IN PROBES
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Date: Mon, 22 Apr 1996 09:11:52 -0700
> From: Jim Breeyear <jbreeyea@moose.uvm.edu>
> To: ammrl@bloch.cchem.berkeley.edu
> Subject: probe insert
>
> We have Bruker probes. ... I have noticed some scratch marks at the inside
> bottom of the inner-most glass insert. ... The scratches dont go completely
> around the insert. Has anyone noticed this situation past or present? ...
On our WM-360 several years ago, the tiny (~7 mm o.d.?) O-rings between the
top & bottom parts of the shim stack got leaky & apparently sprayed some
spinner air _sideways_ against the upper part of the NMR tubes, causing them
to wobble & causing scratching on the bottom inside of the inner-most glass
sleeve of the probe. One side _might_ have been scratched more heavily, but I
don't recall. We went nuts trying to trouble shoot this. Someone at Bruker
suggested the O-rings, we replaced them, and the problem cleared up.
The 2 O-rings seal together 2 air channels running down the shim stacks.
These channels carry spinner air and eject air.
NEAT LABELS ON NMR TUBES
^^^^^^^^^^^^^^^^^^^^^^^^
> Does anyone allow id. labels on the top part of the tube or do you take
> them off before inserting. ...
We leave them on, provided that the labels are really symmetrical. If in
doubt, we take them off.
FWIW, my favorite recipe for attaching labels is this:
1. Cut the paper label so that width is slightly less than Scotch tape, &
length is about 0.2 to 0.5 mm shy of wrapping around the NMR tube _exactly_.
2. Start wrapping the NMR tube with the tape, stopping when you have
exactly 1 layer on.
3. Put the edge of the paper label evently against the "starting edge" of
the tape, & continue wrapping tape.
4. Cut off the tape at the point where you have exactly 3 layers of tape
on the tube.
Over the NMR tube you end up with 1 layer of tape, covered with 1 layer of
paper, covered with 2 layers of tape. It's very well balanced, and the label
is quite legible. I use this for permanent labels on tubes containing
custom test/tune-up samples. FWIW, a laser printer and a 5-point sans-serif
font will allow you to put a lot of legible information on the label.
Hope this helps. -- Gerry
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Gerald A. Pearson INTERNET: gerald-pearson@uiowa.edu
Chem. Dept., Univ. of Iowa OFFICE: 319-335-1336
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