Patent ID: 8921785

Claim:
An assembly of cooperating capillary and cap for containing an aqueous solution in an inner volume of the capillary, the assembly being used in a high pressure freezer in which the aqueous solution is frozen at a high pressure to form an amorphous frozen sample at a cryogenic temperature, the inner volume of the capillary having a diameter of less than 500 μm, preferably less than 350 μm, and the cap forming a closure to one end of the capillary; wherein the part of the cap that is in contact with the inner volume of the capillary when the cap forms a closure, shows an indent, and the capillary has a sharp needle end fitting in the indent of the cap, as a result of which the cap, after freezing the aqueous solution, can be removed from the capillary and a free standing pillar of frozen aqueous material extends from the capillary.