Chemical / Environmental Engineering

Coliform Enumeration Multiple Tube Fermentation (MTF) / Most Probable Number (MPN) Method

Question: A 5-in-series set of test tubes had the following results: 55411. The first result is the number of positive tubes for the 100 dilution and the subsequent results are for 10-fold successively more dilutes tubes. The tabled value to look up in Standard Methods would be based on which series:

5-5-4

5-4-2

5-4-1

4-1-1