Testing of Semisolids - like ointments, lotions and gels - is often a difficult and time consuming work. In this case, the so called "Vertical-Diffusion-Cell" - also known as "Franz-Cell" - is the first choice. But it is difficult to realize a stable flow-through and heating at the Franz-Cell! The "Immersion-Cell" is suggested from the USP, Chapter <1724> as alternative for the testing of semisolids. Although the Immersion Cell is easy to use with the USP-Apparatus 2 (Paddles), it is less known.


The advantages of the Immersion-Cell are:

  • Usable in each Dissolution-Tester (of all brands) with a 200mL - Small Volume Paddle Conversion Kit with a flat bottom vessel.
  • Easy filling of the Semisolids into the Immersion-Cell. The wished Volume is adjustable.
  • Easy fixing of the membrane.
  • Easy heating witht the water bath of the Dissolution Tester.
  • Dissolution with the Paddle-Method, no fragile flow-through-principle.
  • Sampling as with the paddle-method (manually oder automtically).


Membranes are available in PVDF, Tuffryn Polysulfone and Strat-M Membrane.