1. Figure 5.1 A schematic representation of the boundary layer adjacent to the surface of a dissolving solid and the change in concentration of solute across it.

2. Figure 5.2 Dissolution apparatus 1 (basket, right) and apparatus 2 (paddle, left).

3. Figure 5.3 Dissolution curves for indomethacin tablets stirred at 50 and 100 rpm (data redrawn from Klein (2006)).

4. Figure 5.4 Concentration versus time profile for a solute undergoing dissolution following addition to water and (inset) the linear rate region when C = S t /10 (i.e. sink conditions).

5. Figure 5.5 pH across the diffusion layer for dissolution of salicylic acid in various media, showing that the pH at the surface of the dissolving solid can be significantly different from that of the bulk solvent (redrawn from Serajuddin and Jarowski (1985), with permission from John Wiley & Sons, Inc.).