The following article has been authored by John Heaney.
Push-on style baskets have been used for dissolution testing for quite a few years at this point. While they’re generally accepted as equivalent to the clip style baskets pictured in USP <711>, it’s important to be aware of the differences between the two designs. Both have some advantages and disadvantages depending on the method.
The clip style is officially recognized in <711>, so there is never any debate as to whether the clip style baskets are acceptable for testing. Furthermore, all the wetted materials are 316 Stainless Steel, which is chemically compatible with most dissolution methods. The disadvantages with clip style baskets comes down to the clips themselves. The clips can bend either through mishandling or wear over time which would require readjustment. Additionally, it can be difficult for new users to install and remove the baskets without damaging the basket if the clips are holding the basket with uneven pressure.
Push-on style baskets are considerably easier to use as an o-ring holds the basket in place during testing rather than clips. This makes installing and removing the basket far easier (and less chance of damage) as there is consistently even pressure all around the basket. In addition, it also makes them an excellent choice for fully automated systems as there are no clips to wear or grab the basket unevenly. However, the o-ring, while often made of chemically inert material, does introduce another wetted material into the dissolution test which needs to be accounted for during method development.
In most cases dissolution results between push-on baskets and clip style baskets will be identical. However, that can be formulation dependent, and if a test is sufficiently sensitive it is prudent to test both styles of baskets to ensure the results are identical if both types are present in the same lab.