Deviating Samples

Deviating Samples

For all works undertaken the laboratory has a responsibility to assess the suitability of samples provided for the testing.  Where a sample is unsuitable for the specified analysis it may be classed as deviating.

Where a sample has been identified as deviating the integrity of the results may be affected. This means results from the analysis could be lower, or higher than the true value of the original sample.

There are several factors that can cause a sample to become deviating, these include:

  • Sampling Times – For environmental determinations there are recommended time limits between the sampling and analysis of each compound. Where these limits are exceeded the sample becomes deviating, Thus it is important that once the samples have been taken they are delivered to the laboratory as soon as possible.
  • Suitable containers – Dependant on the analysis required the type of container needed will vary. Please click here to see guidance on container types.
  • Storage Conditions – Once sampling is complete samples should be kept at below 4oC to maintain their integrity. This can be done by keeping the samples in ‘Cool boxes’ which also have frozen ice packs within them. Where samples are received above this temperature they are considered to be deviant.
  • Headspace – This is linked to the types of containers and specific to volatile determinants. It is important when volatile determinants are scheduled that the container is filled to the brim with the sample. Where there is a gap it creates a ‘Headspace’ into which the samples can permeate, thus reducing the concentrations within the soil.

Analysis can be carried out on samples identified as deviating samples.  Test reports include notes to identify test results on deviating samples

For further information please Contact the Laboratory