Positive and Negative Control

agy lee agyleesy at hotmail.com
Thu Dec 18 10:57:25 EST 2003

I'm doing a Total Bacteria test using the pour plate method.
As part of the QA/QC, I will be incubating:
a) the TB agar alone; and
b) the TB agar with the dilution water as a sample.

I will also have a positive and negative control.  The positive control will 
be a solution containing the dilution water and EColi which will undergo the 
same procedure as a normal sample.

As for the negative control, I'm a little confused. Should it be the 
incubation of a) TB agar only or should it be b) TB agar with dilution water 
as a sample.

As I only want to eliminate the EColi factor, I was thinking of using b) for 
the negative control. Is that right?
Thank you for the help.

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