The R-CARD^® KwikCount^® EC is made to contain the same formulation of nutrients as in the 20 mL bottle of liquid that is included in the KwikCount EC MF Method.  There are at least two ways to utilize the R-CARD KwikCount EC that give the same results as the USEPA-approved method. 

First, the sample can be filtered with the same 47 mm, 0.45μm pore size filter, and the filter containing the bacteria is then placed in the center of the R-CARD bottom (top lifted) and 1mL of sterile buffered or deionized water is deposited on the top of the membrane. The R-CARD top piece is then lowered onto the wet filter, which is incubated for 7-10 hrs (41±0.5°C) as is the approved dish, removed, and subjected to long wave (366nm preferred) UV light in a darkroom.  Any E. coli will fluoresce and be easily counted, just as in the KwikCount MF EC EPA-approved method.

Easier yet, the aqueous sample can be diluted in sterile water or sterile buffered water so that each mL contains an appropriate number of the target E. coli (recommended 20-100 CFU/mL).  Then, using a sterile 1mL dropper, lift the top piece of the R-CARD®, deposit 1 mL of the diluted aqueous sample on the middle of the bottom piece, and drop the top piece down onto it.  The water will spread into a large circle and gel within 1-3 minutes. Incubate and count as before.  It should be noted that this last approach saves time and money spent on the membrane filter and filtering, as well as the Petri dish cost.

If you wish to use any of the above-described R-CARD methods, you must not assume that they are included in the USEPA-approved Method for Ambient Waters due to the fact that the R-CARD KwikCount EC was still in the process of development when the KwikCount EC MF comparative studies were run.  More recent studies confirm the information disclosed herein.

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