The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Nov. 30, 1993

Filed:

Nov. 13, 1992
Applicant:
Inventors:

Ray W Wood, Elkhorn, WI (US);

Lee D Hansen, Orem, UT (US);

John W Crawford, Salem, UT (US);

Assignee:

Baxter International Inc., Deerfield, IL (US);

Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
G01N / ; G01N / ;
U.S. Cl.
CPC ...
436 34 ; 422 51 ; 422 681 ; 422 8212 ; 422 8213 ; 436 39 ; 436147 ; 436148 ; 436157 ;
Abstract

A method of determining the critical vapor pressure of a hygroscopic material, such as a drug. A drug sample is placed in a substantially isothermal environment. A vapor, such as water vapor, at a given pressure is then placed in the ambient air over the drug. The rate of heat production from this sample at the given water vapor pressure, or the humidity of the air above the sample, is then measured. The water vapor pressure over the drug is gradually increased. Simultaneously, the rate of increase in heat production from the drug sample, or the rate of change of the relative humidity of the air above the drug sample, is measured. A marked increase in the rate of heat production generated by the drug, or a marked change in the relative humidity of the air over the sample, signals the attainment of the critical water vapor pressure.


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