Serving Scientists Since 1994

Apparatus 1 - Running the Test

Running the Test


A basic sequence of events takes place when running the rotating basket test

  • Inspect and Prepare the Dissolution Tester
  • Prepare Media
  • Deliver Media
  • Check Temperature
  • Prepare for Sampling
  • Introduce Dosage Forms to Baskets
  • Lower Baskets in Media
  • Run Test
  • Take Samples
  • Measure Samples


Inspect and Prepare Dissolution Tester

The operator should prepare the tester for use, ensuring that all parts are clean and dry and that there are no defects with any of the parts. A defect includes scratches, bends, small dents etc.

It is a good idea to ensure that all baskets, shafts, vessels, etc, remain in the same position for each test - it makes it easier to identify issues should things go wrong.

All parts should be serialised and those numbers noted prior to use. If any parts have been changed since the previous test then those parts should be verified to fall within the guidelines.


Prepare Media

The media should be prepared according to the requirements, and properly degassed using either the USP method, or another suitable method to remove dissolved gas.

Degassing is particularly important with baskets since bubbles will stick to rough surfaces first and baskets in particular. Bubbles on basket mesh will impede media movement and affect the test.


Deliver Media

Media should be the correct volume within 1% (all volumes are measured at 20-25 degrees), and dispensed into the dissolution vessel, taking great care to minimise the introduction of air or agitate the media.

Volume measurement can be by weight, or by a suitable calibrated volumetric flask. Measuring cylinders are sometimes used but these are likely to be outside of the required accuracy specification

Check the Temperature.

The temperature of the media should be 37oC +/- 0.5oC. This should be checked in each individual vessel and ideally the temperature should be the same in all of them. Note that the actual waterbath temperature may need to be set above 37oC in order to achieve the correct temperature inside the vessels. Note also that lowering the baskets into the media will temporarily decrease the media temperature by a small amount. It is therefore a good idea to ensure that all vessels are actually at 37oC before the test begins and not lower.

If the media is going to stand for any length of time before the test starts then cover the vessels with vessel covers to reduce evaporation.


Prepare for Sampling

If manual sampling then prepare clean and dry sampling cannulae, syringes and filters. Use only reproducible and certified filters to avoid contamination issues and ensure reproducibility. It is a good idea to use pure polypropylene syringes (not those with a rubber tip plunger), or clean glass syringes.

Prepare containers for samples, labelled for each vessel position.


Introduce Dosage Forms to Baskets

Place the dosage forms in the clean, dry baskets using forceps or gloves. The dosage form should not have been left on the open bench prior to this step, but stored in a suitable container to prevent possible moisture interaction.

The basket with dosage form should be attached carefully to the basket shafts, taking care not to bend the clips. Only handle the baskets by the rim and not the mesh to avoid deforming the basket.


Lower Baskets into Media

Without leaving the dosage forms in the baskets for an extended period, start the test by lowering the baskets into the media. If manual sampling, it may be necessary to stagger the start time in order to accommodate the sampling time for each vessel. Automated systems sample at the same time simultaneously and therefore all baskets can be lowered together.

Inspect the baskets to ensure that no bubbles are trapped inside or under them.

Record the start time for each basket to calculate the required sampling time.

Run the Test

During the test is a good idea to visually inspect each test position. It is often immediately obvious if there are problems developing, and any observations should be noted to record against possible concentration deviations later.


Take Samples

Samples are taken at the required time point within a 2% window. This does not allow a lot of time if manual samples are being taken - hence the need to stagger the start times. The sample should be taken and filtered immediately - see sampling section for sampling technique and filtration.


Measure Samples

Once the samples have cooled, measure according to the defined analytical method. If HPLC is to be used then the samples may require an additional filtration step before that



A good and successful dissolution test relies on accurate preparation. If all else is equal then if the preparation is right then most test proceed without any issues.


Next Page - Apparatus 2, The Rotating Paddle


Related Products

Dissolution Filters
Sampling Cannulae
Dissolution Vessels
Dissolution Baskets