A Device for Sealing NMR Samples under Vacuum It is often desirable to seal nmr tubes under vacuum. However, the task of sealing thin-walled nmr tubes to vacuum line glass demands a certain amount of glassblowing skill. This device reduces the problem to one of sealing the tube with a small cool flame. In this way many sulfur dioxide solutions have been prepared and air sensitive samples handled. A new nmr tuhe may he used twice and when finally cut open is still long enough far use with normal samples. The components are: a thermometer holder (1) [Quickfit part no. ST 51/13 or equivalent], the silicone rubber ring of which (3) may need to be replaced with one specially cut for use with 5mm nmr tubes (5); and an asbestos heat shield (4) fitted with two metal clips (2). The tube should be cooled to a low temperature in order to create an effectivevacuum in it before it issealed with the torch.
P. McArdle University College Galway, Ireland
124
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Journal of Chemical Education
