Wagtech™ Potakit

The membrane filtration (MF) method can be used to reliably test large numbers of water sample, and is US EPA approved for measuring coliforms.

The water sample is filtered through the membrane filter using a vacuum to pull the water through the membrane. The membrane filter is then placed onto a nutrient source gel in a petri dish and incubated for 24 h at 37 °C. The Coliform and non-Coliform colonies can then be counted. Often pH indicators are used to distinguish between different colony types.

‘Analyte’ and ‘Parameter’ are scientific terms for something you want to measure.  For example, the analyte may be nitrate and as a parameter it would be nitrate concentration. Take a look at our parameter pages which include an overview of the test parameter, it’s presence in different applications and information on testing.

‘Species’ is used to refer to the atom, molecule or part of a molecule being tested for. In the nitrate example above, the result could be given as N or as NO_3. It is important to be specific, especially when comparing different results.

‘Units’ refer to what the result’s numbers are.  Commonly, we use milligrams per litre (abbreviated to mg/L).  Parts per million (ppm) is also used as an equivalent in many industries.