Good dissolution vessels are critical in obtaining correct and reproducible results and are sometimes overlooked as a key element in the dissolution test.
All vessels meet the physical dimensions of the USP and have a hemispherical bottom which means that they should be perfectly rounded with no obvious defects of the glass on the inside. Wall thicknesses should be even and reproducible.
Although the USP states the dimensions for vessels, the tolerances are actually quite wide, meaning vessels associated with various dissolution baths are not dimensionally the same. Replacing a vessel with one not specifically designed for the instrument could impair vessel centering and paddle height. Also larger or smaller inside diameters can affect vessel hydrodynamics.