Colilert Questions and Answers
Why is the Colilert product irradiated?
We offer low-level gamma-irradiated Colilert product to improve quality and eliminate possible contamination from coliform bacteria. View FAQ's on Irradiation
What are the recommended storage conditions?
2-30°C away from light.
What is the Colilert Comparator?
The Colilert Comparator is a liquid color reference. Its purpose is to
assist in distinguishing a minimal positive from a negative test result.
How do you use the Colilert Comparator?
At 24-28 hours, compare each reaction vessel against the color
comparator. Any yellow color or fluorescence equal to or greater than
the comparator is considered positive.
What should the color of the Colilert powder
be?
The Colilert reagent powder should be dry, free flowing and white to
off-white in color. Any concerns about the color of the powder or
integrity of the powder should be directed to IDEXX Technical Service.
Can Colilert samples be read after 28 hours?
Yes, if they are negative. If an inoculated Colilert sample is
inadvertently incubated over 28 hours, lack of yellow color is a valid
negative test; a yellow color after the 28 hours is not valid and should
be repeated or verified.
Can Colilert samples be read before 24
hours?
Yes, if they are positive. An inoculated Colilert sample that is
positive for coliforms and E. coli before 24 hours is a valid
positive test for both coliforms and E. coli. If the sample is
positive before 24 hours for coliforms only, the sample is a valid
positive test for coliforms. However, the sample should be incubated for
a longer period (up to 24 hours, but not greater than 28 hours total
time) to determine whether E. coli are present.
Why is the test limited to a 24- to 28-hour
incubation?
The reagent system was designed to suppress non-coliform ONPG or MUG
positive bacteria for at least 28 hours. If incubation extends past 28
hours, it is possible that such bacteria will overcome Colilert's
suppression system and react with ONPG or MUG. When incubation exceeds
28 hours, only negative results are valid. Positive results must be
confirmed by classical methods.
Can I quantify my Colilert results?
Yes, Colilert can be run with Quanti-Tray®, Quanti-Tray®/2000
or any multiple tube format.
What are the disposal requirements for a
Colilert sample?
Check with your local, state and/or federal authorities for proper
disposal of bacteriological biohazard materials at your facility.
Is Colilert approved by the U.S. Environmental Protection Agency (EPA)?
Yes. Colilert is U.S. EPA-approved for drinking water
presence/absence(P/A) and Most Probable Number (MPN) and for source
water. Pertinent references:
- June 29, 1989 U.S. EPA Federal Register Colilert coliform approval
- June 10, 1992 U.S. EPA Federal Register Colilert E. coli
approval
- July 17, 1989 U.S. EPA Federal Register Colilert Most Probable Number
(MPN) approval
- July 1, 1994 Code of Federal Regulations Colilert Source Water
approval
What is the detection limit of Colilert?
Colilert detects total coliforms and E. coli at 1
organism/100 mL.
What is the shelf life of Colilert?
Colilert shelf life is up to 12 months from the date of
manufacture for the Snap Pack formats (100 mL and 50 mL) and up to 15
months from the date of manufacture for glass tube formats (10 mL and
250 mL).
|
