USP Apparatus – Dissolution Testers – What are the different types?

dissolution testersFor someone new to the field of dissolution and the workings of dissolution testers, the first thing you’ll need to know is what the different test apparatuses are that the machines can use.

The United States Pharmacopoeia, or USP for short, is often the primary regulating authority referenced when detailing the various dissolution testing apparatuses available.

Each type of dissolution test will have a method and apparatus associated with it. The apparatus is identified with the abbreviation USP, followed by a number. Here we will detail the common USP apparatuses and what they actually mean.



USP Apparatus


This is a small basket attached to the shaft that contains the sample. The shaft and basket spin inside the test media.


This is the most common form of dissolution testing, where a flat paddle is attached to the shaft and spins in the test media. The sample is dropped into the media vessel and it sinks to the bottom.


This where the use of a reciprocating cylinder is employed. A sample is paced inside a glass tube with a mesh base and moved up and down in the media vessel.


This is where the sample is placed inside a static cell, called a flow-cell, and the test media is pumped through the cell in a continuous flowing motion, often referred to as flow-through. You can have different cells for different sample types.


This is the paddle-over-disk method. A USP 2 paddle is attached to the shaft, and a mesh disk is placed at the bottom of the media vessel beneath it. The sample is placed beneath the disk, holding it in place.


This is the use of a rotating cylinder. Often a patch is stuck to the outside of the cylinder, which is attached to the shaft and spins.


This is the reciprocating disk method. A disk is attached to the shaft which is raised and lowered in the test media. The sample sits above the disk.

Total Laboratory Services Ltd can supply you with dissolution testers, along with their parts and accessories, so please contact us with your requirements.