Abstract
The critical relative humidity (Hcr) of 25 drugs and chemicals was determined by the air humidity in equilibrium (AHE) method. The relationship between the Hcr and the solubility was explored theoretically, and the Hcr was calculated according to the nonelectrolyte Wilson nonrandom factor (N-Wilson-NRF) model or Raoult’s law from their solubility. The results indicate that the calculated Hcr is comparable to the measured one.
Declaration of interest
The authors are grateful to the National Natural Science Foundation of China for financial support.