Deviating Samples

This is a mandatory action which all accredited laboratories have been required to implement by UKAS.

Details relating to this requirement can be found by following the link below and reviewing TPS63: www.ukas.com/technical-services/publications/technical-policy-statements-3

This policy requires a testing laboratory to clearly state on the final certificate of analysis any samples that may have been compromised in any way. The samples suitability for testing may be effected by the storage condition from sampling to delivery to the laboratory, then the storage conditions within the laboratory, the time between sampling and analysis, and the use of appropriate sampling containers.

Once a sample has been received by our laboratory the sample will be maintained in an under appropriate conditions.

A guide to appropriate sample conditions is shown below:

Legionella samples:

Collect samples into a sterile bottle containing sodium thiosulphate

Store in the dark at room temperature

Return to the laboratory as soon as possible after sampling, ideally within 2 days but always within 5 days of sampling.

All other microbiology:

Collect samples into a sterile bottle containing sodium thiosulphate

Store in the dark and at approximately 4oC (cool box will be satisfactory)

Return to the laboratory as soon as possible and within 24 hours.

Chemical samples;

Due to the range and variation of chemical analysis it is not possible to provide general requirements for the preservation and transportation of chemical samples as these can vary considerably. Details on individual tests can be obtained from the Standing Committee of Analysts (SCA) Blue Books by visiting:

https://www.gov.uk/government/publications/standing-committee-of-analysts-sca-blue-books

It is always good practice to return samples to the laboratory as soon as possible after collection.

 

Mercian Science will add the following comments when a sample is found to be deviating:

  1. When there has been a delay between sampling and analysis: “This sample has exceeded the recommended time between sampling and receipt and therefore the results provided may be compromised”.
  2. When the storage temperature cannot be assured: “This sample was received at an inappropriate storage temperature and therefore the results provided may be compromised”.
  3. When samples are received in an inappropriate container: This sample was received in an inappropriate sample container and therefore the results provided may be compromised.
  4. When the date of sampling has not been provided: “The date of sampling has not been provided and therefore the sample may have exceeded the recommended time between sampling and receipt hence the results provided may be compromised”.