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Culture Collections

PHE LENTICULE® disc Reference Materials (RMs) and Certified Reference Materials (CRMs)


Frequently Asked Questions (FAQs)


1. What is the difference between RMs and Certified Reference Materials (CRMs)?

CRMs must be traceable to an accurate source, in this case a culture from the National Collection of Type Cultures (NCTC) or the National Collection of Pathogenic Fungi (NCPF).  CRMs must be accompanied by a certificate that establishes the traceability at a stated level of confidence. There are less stringent requirements for the traceability and certification of RMs. PHE LENTICULE disc CRMs are certified for the species and the level of microorganisms (it is important to check the growth conditions described on the certificate of analysis for the certified level per LENTICULE disc).


2. Why are some PHE products designated CRMs and some as RMs?

In future, all the PHE LENTICULE disc RM products will be designated as CRMs and will be included in the scope of our accreditation to ISO Guide 34:2009. However, there are still a small number of products that have not yet been added to the accreditation scope so those will continue to be designated as RMs for the next few months.


3. What can I use the PHE CRMs for?

PHE CRMs can be used for quality control of culture media and for process controls (including the preparation of spiked samples). Information about use is provided in the certificates.


4. Can I have a copy of the UKAS accreditation certificate?

You can download a copy of the ISO Guide 34:2009 UKAS accreditation certificate (opens in new window).


5. How do I access my Certificates of Analysis?

Certificates of Analysis are available to download from the Culture Collections website.  Go to the web page for the specific product and click on the ‘Certificate of Analysis’ hyperlink.  You will need to enter the batch number to retrieve the relevant Certificate of Analysis.  The batch number is on the product labels.  View an example of a Certificate of Analysis (opens in new window).  


6. Do I have to validate the CRMs?

PHE CRMs contain microorganisms that are directly traceable to NCTC strains. We have demonstrated successfully that the processes used to prepare the CRMs do not interfere with the characteristics of the NCTC control strains. You do not need to confirm the identification. However, if you use the CRMs for enumeration processes other than those stipulated in the CRM certificate then you may need to prepare validation data.  For example, if you use a different culture medium or additional step, such as membrane filtration, the colony forming units recovered may differ to the level reported on the certificate of analysis.


7. What do the CRMs look like?

PHE CRMs are supplied in LENTICULE disc format. They consist of small discs that are packed in labelled plastic tubes over a desiccant. The CRMs are coloured so they can be seen more easily. Instructions for handling are provided with every order.


8. How do I store the CRMs and what happens if I store them incorrectly?

The CRMs should be stored at -20±5ºC as soon as they are received in your laboratory. They are stable for short periods of time at ambient temperatures and will not normally deteriorate during transit. However, you should not store your PHE CRMs in the refrigerator or at ambient temperatures. Prolonged storage at temperatures other than -20±5ºC will cause a deterioration of the product.


9. What is the shelf-life of the CRMs?

The CRMs are stable for at least one year from the date of manufacture.  All PHE CRMs are individually packed and labelled clearly with the batch number and the expiry date.


10. How will I get general help or technical support?

General Enquiries

If you have queries or concerns about your order, delivery dates or product availability please contact us.


Our technical support team will be able to answer your queries directly or will contact our specialist microbiologists if you require more specific advice.


Please note: If you purchased your LENTICULE discs from one of our distributors, you should contact the distributor first with your queries.


You can download a pdf copy of these frequently asked questions.


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