ISO 9308-2:2012 PDF Download

ISO 9308-2:2012 is a standard that outlines a method for determining the quantity of Escherichia coli (E. coli) and coliform bacteria in water using the Most Probable Number (MPN) technique. This method involves growing the targeted organisms in a liquid medium and calculating the MPN using MPN tables. It is applicable to various types of water, including those with high levels of suspended matter and background counts of heterotrophic bacteria, but it is not suitable for marine water.

The method relies on the detection of E. coli based on the presence of the enzyme b-D-glucuronidase. Therefore, it may not detect certain enterohaemorrhagic strains of E. coli that do not express this enzyme, as well as a small number of other E. coli strains that also do not express b-D-glucuronidase.

ISO 9308-2:2012 emphasizes the sequence of tests used to detect and confirm the presence of coliform bacteria, including E. coli. The level of confirmation required may vary depending on the nature of the water being analyzed and the purpose of the examination. However, this standard provides a confirmed result without the need for further confirmation of positive wells in the testing process.