1989 Volume 37 Issue 5 Pages 1362-1365
The dissolution of sieved n-propyl p-hydroxybenzoate crystalline particles mixed at various weight ratios devised to give symmetrical particle size distributions was conducted under the sink condition. These dissolution processes were simulated on the basis of the change of surface area estimated for the component samples. The mixed ternary systems were converted into several imaginary symmetrical particle-size-distributed systems, and the dissolution processes of the original mixed systems were simulated with the imaginary systems by making use of the relationship between the surface-producing rate constant and the initial particle size. The validity of the simulation on the bases of the surface-producing rate constant and the introduction of imaginary particles was also examined. The simulated values showed fairly good coincidence with those measured. The values simulated by the use of the changes of surface area during the dissolution, obtained by graphical integration for the components, were closer to the measured values than those simulated by the use of the relationship between the surface-producing rate constant and the initial particle size. However, the latter simulation method was thought to be more useful than the former, because the surface area produced during the dissolution is given by a generalized function of the initial particle size and the dissolution behavior of mixed systems was predictable when the initial particle size of the components were defined in advance.
