gamma irradiated prepared media plates for environmental monitoring in pharmaceutical manufacture, cleanrooms and more

Gamma Irradiated Prepared Media

In addition to our standard range of Redipor® media projects, we also offer triple-wrapped irradiated settle plates, petri dishes and contact plates in 55mm, 90mm and 140mm options. Gamma irradiation extends shelf-life typically to 6 months in ambient conditions.

All irradiated products are subjected to the same rigorous quality checks as our standard pre-poured plates. Once packed, they then pass through an additional sterilisation process.

Finally, they are tested after irradiation to confirm growth properties and pH. A detailed QC certificate is provided with each batch.


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Cherwell gamma irradiated media and packaging

Media and packaging solutions: contact us to place your order

Gamma irradiated media

Contact plates, Petri dishes and settle plates in 90mm and 140mm sizes. Vials also available

Gamma irradiated barrier pack

Range of VHP gas impermeable packaging for gamma irradiated Redipor® media products.

Triple packaging for irradiated media

Triple layer packaging is available for all irradiated products on request

We provide gamma irradiated products to many organisations

Some of our clients



Asked Questions

Why might I want gamma irradiated media?

The sterility of the packaged medium is assured and all but the outer layer of packaging is also sterile. Thus the risk to the environment to be sampled is greatly reduced.

There is an additional benefit that the additional packaging and process extends the room temperature shelf life. This can be sufficient reason for small or irregular users to prefer irradiated.

We need a specific or bespoke media type. Can Cherwell help?

Our Redipor Prepared Media range is so extensive that not every product is included in the official price list. In addition to offering such a wide selection of products, we have developed a flexible manufacturing process enabling us to produce bespoke solutions.

Contact us to discuss your requirements, whatever they are.

Do I need to store my prepared media in the fridge?

The majority of our prepared media can be stored in ambient conditions, not exceeding 25ºC. There are only a small number of very specialist products that require different storage conditions.

We have never specified refrigeration as a storage condition for our general media as this causes excess condensation and can result in very wet agar, rendering it impossible to use.

What is the maximum exposure time for settle plates?

Settle plates are used to monitor the level of viable particles in the environment through a process of passive air sampling. A viable particle settles on agar plates at a rate dependent on its characteristics and the airflow in the environment.

EU GMP Guide Annex 1 has recommended that 90mm settle plates can be exposed in cleanroom environments for up to 4 hours. However, agar plates may dry out during long exposures where the rate of air exchange is high. So, it might be necessary to use deep filled settle plates, or replace the settle plate after a shorter time to ensure satisfactory growth promotion after exposure.

Once we have opened a pack of irradiated plates, how quickly should they be used?

The final wrap of irradiated plates should be removed at the point of use and it is then a question of risk.

For example in a grade A isolator it might be reasonable to rewrap a part pack of plates for use in the next session. If all the exposed plates show no growth it is a reliable result.

However if one or more colonies appear on the plate it might not be possible to know during which session the contamination occurred and the OOT investigation becomes more complicated and expensive.

What does the use by date mean on Redipor® prepared media?

For Redipor media the Use By date is the last day on which the medium should be inoculated or exposed. Any incubation period that is normal for that product may begin on that day. For example a 14 day sterility test in TSB or a 5 day incubation for a TSA settle plate.

What does triple wrap packaging mean?

Not as obvious as it might sound. 3 layers of wrap between the agar plate and the outside world, of course, but Redipor can offer at least 3 different ways to achieve that with our standard product range.

We then have even more bespoke solutions to meet individual needs. Let us know how and where you want to remove the layers and we can find the best solution.

Cherwell is different

Supplying products is only the start


The best products prepared for you

Our Redipor® media products are batch tested, QC certified and delivered when you need them


Bespoke accessories and services

We provide additional equipment or services to make your environmental monitoring more effective


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We build long-standing client relationships on understanding, commitment and trust


get our pocket guide

The Pharmaceutical and Cleanroom Industry's Guide to Prepared Culture Media

A guide to understanding the logistics, best practices and breadth of available prepared media options for varying applications.


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