Hi AMMRL.
I’d like your help with a practical solids NMR problem: removing part of
a cap that’s stuck in a rotor.
An attempt was made to remove a VESPEL cap from a 3.2mm zirconium rotor using
the proper Bruker cap removal tool. In the process, the cap’s top part with
the fins was sheared off, leaving a tight-fitting plastic cylinder in the end
of the rotor. The plastic face is flush with the rotor face, leaving nothing
external to grab.
The bottom part of the cap is a hollow cylinder, so I can reach through it
with a dental tool (which is strong, thin, and bent at the end, enabling the
tip to poke through and pull against the back surface of the cap fragment),
but it’s pretty stuck.
Today we tried immersing it in liquid nitrogen, which I’m told normally lets
caps pop right out, but that didn’t happen, even with coercion via the dental
tool. I’m thinking the cap might be stuck by the thick, gooey sample material
that was in there for an extended period. (We’d dissolved most of the material
with a combination of solvents and sonication prior to attempting extraction.)
Any suggestions? Tips on how to get a good grip on a liquid-nitrogen-frozen rotor
without smashing or scratching it would be appreciated.
Thanks. - Josh
--
Josh Kurutz, PhD
NMR Facility Manager, Chemistry Dept.
University of Chicago
https://chemnmrlab.uchicago.edu/
jkurutz_at_uchicago.edu
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Received on Tue Jul 15 2025 - 17:56:05 MST