Avoiding Glass Contamination in Removing Samples from Evacuated Tubes It is convenient t o store solid samples which decompose in air in small glass vials which are sealed under vacuum with a flame. However it is difficult to remove a sample without contaminating it with imploded glass particles. This may introduce serious errors in subsequent weighing aperations, particularly with small samples. A simple time-honored procedure can be used to avoid this difficulty. The sample is placed in a 7-10-mm Pyrex tuhe which is then evacuated and sealed. Later, the sealed tube is opened by scoring heavily with a file, then touching the scored portion with the tip of a molten glass rod. This causes the crack to travel around the tube, simultaneously releasing the vacuum. The end of the tuhe is broken off with little or no contamination of the sample by glass fraements. lJse of a long tuhe permits subsequent resealing. 'Supported by a National Institutes of Health Postdoctoral Fellowship, 1-F02GM55267-01, General Medical Sciences.
University of Washington Seattle, 98195
Mary T. Pratt
Volume 50, Number 10, October 1973
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