Effects of various hydrodynamic conditions on dissolution rate determinations.
An automated potentiometric procedure was used in dissolution rate studies to determine the effects of various hydrodynamic conditions on dissolution rate determinations. Changes in the hydrodynamics of the system resulted from using various sizes and shapes of dissolution vessels. Dissolution rate constants for benzoic acid prills in distilled water at pH-stat 6.2 were used as a measure of the agitation intensities present in the different shaped vessels. Great variations in the dissolution rates occurred in vessels with the same diameter and stirrer blade position when the shapes of the bottom of the vessel were varied. A similar order of dissolution rates was obtained at 100 and 150 rpm for the individual vessels at various propeller heights. The order differed from one vessel to another, depending on the shape of the bottom (concave, convex, or flat) of the vessel. In some cases, a change in the type of bottom resulted in the opposite order of rates for vessels with the same diameter.
Effects of various hydrodynamic conditions on dissolution rate determinations. An automated potentiometric procedure was used in dissolution rate studies to determine the effects of various hydrodynamic conditions on dissolution rate determinations. Changes in the hydrodynamics of the system resulted from using various sizes and shapes of dissolution vessels. Dissolution rate constants for benzoic acid prills in distilled water at pH-stat 6.2 were used as a measure of the agitation intensities present in the different shaped vessels. Great variations in the dissolution rates occurred in vessels with the same diameter and stirrer blade position when the shapes of the bottom of the vessel were varied. A similar order of dissolution rates was obtained at 100 and 150 rpm for the individual vessels at various propeller heights. The order differed from one vessel to another, depending on the shape of the bottom (concave, convex, or flat) of the vessel. In some cases, a change in the type of bottom resulted in the opposite order of rates for vessels with the same diameter.