Importance

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Abstract

A solvent-containing biological material specimen is dried in a vacuum chamber with solvent evolving during the drying cycle being condensed in a refrigerated cold trap. During the drying cycle, communication of the drying chamber with the vacuum pump with which the chamber is evacuated, selectively is established or interdicted in response to raising or lowering of the vacuum condition in the chamber with respect to an initially set predetermined vacuum condition. Evolving of solvent from the specimen proceeds during interdiction by way of 'cryopumping' due to the differential in pressure between the chamber and the refrigerated trap. Thus maximized solvent recovery in the trap is achieved, and carry over of solvent to the vacuum pump wherein its presence would be contaminating of the pump oil is for practical purpose eliminated. Selective establishment and interdiction of chamber/pump communication provides a controlled vacuum drying operation and lessens 'bumping' or foaming of certain highly volatile solvents and volatile biological material as well which if occurring, can cause defects or altered character in the specimen. A unique arrangement of a pair of two-way valves is employed to effect and maintain vacuum control as well as control bleeding of a gas to the chamber and pump at the end of the drying cycle.

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First Claim