Duplicate split samples for internal quality control in routine water microbiology |
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| Authors: | N.F Lightfoot H.E. Tillett P. Boyd S. Eaton |
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| Affiliation: | Public Health Laboratory, Institute of Pathology, Newcastle General Hospital, Newcastle upon Tyne;PHLS Communicable Diseases Surveillance Centre (CDSC), London, UK |
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| Abstract: | In the microbiological examination of water, indicator organisms are sought by membrane filtration of 100-ml sub-samples of water. The same sample cannot be examined twice but the use of split samples, where two 100-ml sub-samples from the same batch are processed, has been explored. Binomial theory was used to determine the 95% confidence intervals for the results obtained. Two sets of 50 results were assessed by the method and the resulting control charts are illustrated. |
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