USP and FDA Requirements for Basket Apparatus The basket apparatus consists of a wire-mesh basket that is attached to a rotation shaft, which is then immersed into a dissolution vessel for the duration of the dissolution test. Since the dosage unit is in direct contact with the basket, the physical dimensions and motion of the basket can have a dramatic effect on the dissolution rate of the solid dosage unit. Because of the critical nature of the basket, it is tightly controlled by several mechanisms. First, the dimensions of basket height, i.d. and o.d. of the basket opening, height of the open screen, and size of the mesh are specified in USP <711>. Next, the amount of wobble at the bottom of the basket while rotating is checked with a wobble meter at periodic intervals anywhere from time use to once a year, to ensure that it is within the 1-mm specification indicated in USP <711>. Finally, a functional test using standardized performance-verification tablets is executed. The rate of release of the standardized calibrator tablet is measured and compared to the acceptance criteria. The performance verification tablets and acceptance criteria are designed so that if the apparatus is not set up in accordance with the tight USP specifications, it will not pass this final test