Chemistry: analytical and immunological testing – Rate of reaction determination
Patent
1992-11-13
1993-11-30
Johnston, Jill A.
Chemistry: analytical and immunological testing
Rate of reaction determination
422 51, 422 681, 422 8212, 422 8213, 436 39, 436147, 436148, 436157, G01N 716, G01N 2520
Patent
active
052664929
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.
REFERENCES:
patent: 3833340 (1974-09-01), Jones et al.
Strickland, W. A., Jr., "Study Of Water Vapor Sorption By Pharmaceutical Powders," Journal of Pharmaceutical Sciences, vol. 51, No. 4, 1962, pp. 310-314.
Michniak-Mikolajczak, B. B., et al., "A Microbalance Technique For Measuring Water Vapour Uptake And Release By Stratum Corneum In Vitro," International Journal of Pharmaceutics, vol. 31, 1986, pp. 247-259.
Crawford John W.
Hansen Lee D.
Wood Ray W.
Baxter International Inc.
Flattery Paul C.
Johnston Jill A.
Rockwell Amy L. H.
Schaafsma Paul E.
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