A method for determining the solution rate of fine particles

Abstract

Abstract A method is presented for determining the solution rate of fine particles, crystalline hydrocortisone acetate being used as the model substance. The method’s innovation is that it takes account of the changing particle size distribution during the solution process, using a Coulter counter to observe this. The solution rate may be expressed as diameter loss per unit time (dt = do – k2t). The solution rate of hydrocortisone acetate under the conditions of the experiment was found to be linear and to correspond to a diameter loss of 1.68 μ/hr, equivalent to 108 μg/cm2 of surface/hr. Corrections for the Noyes-Whitney effect were made.