Principle: Uses proprietary Defined Substrate Technology (DST) nutrient indicators - ONPG and MUG
Approvals: U.S. EPA Approval; ISO 9308-2:2012
Suitability: Detction of both total coliforms and Escherichia coli in water
Capital equipment required: Yes
Colilert-18 is a liquid culture method that simultaneously detects both total coliforms and Escherichia coli in water, giving confirmed results in 18 hours.
Principle: The Colilert-18 test uses proprietary Defined Substrate Technology (DST) nutrient indicators ONPG and MUG to detect coliforms and E. coli. Coliforms use their β-galactosidase enzyme to metabolise ONPG and change it from colourless to yellow. E. coli use β-glucuronidase to metabolise MUG and create fluorescence. Since most non-coliforms do not have these enzymes, they are unable to grow and interfere. The few non-coliforms that do have these enzymes are selectively suppressed by the Colilert-18 test’s specifically formulated matrix.
Approvals: U.S. EPA Approval: Colilert-18/Quanti-Tray has US EPA Approval for detection of coliforms and E.coli in Drinking Water, Surface Water Ground Water and Waste Water.
ISO 9308-2:2012: Colilert-18 is the ISO 9308-2 standard for Water Quality - Enumeration of Escherichia coli and coliform bacteria - Part 2: Most probable number method.
Colilert-18, (ISO 9308-2) is a reference method in the European Drinking Water Directive 2015/1787
AFNOR NF Validation (IDX 33/01-11/09) - Colilert-18/Quanti-Tray is validated for the enumeration of β-glucuronidase positive Escherichia coli and β-galactosidase positive coliform bacteria in drinking waters for human consumption.
SCA Blue Book: Colilert-18 is specified in Microbiology of Drinking Water (MoDW) Part 4: Methods for the Isolation and enumeration of coliform bacteria and Escherichia coli (including E.coli O157 H7) (2016) - Colilert®-18 (Method D).
A more exhaustive list of approvals is available on request
- Identifies E. coli specifically, avoiding unnecessary remedial action caused by non-target organisms.
- Suppresses up to 2 million heterotrophs per 100 mL.
- Eliminates the subjective interpretation found with traditional methods.
- Detects a single viable coliform or E. coli per sample.
- Under 1-minute hands-on sample preparation time.
- Detects coliforms and E. coli simultaneously in 18 hours or less.
- No confirmations needed.
- No glassware cleaning or colony counting.
- Ease of use simplifies training.
- Unit-dosed packaging eliminates media preparation.
- No repeat testing due to clogged filters or heterotrophic interference.
- Quality Control (QC) procedure can be done in 15 minutes.
- Faster results mean that you can act sooner to prevent the spread of contamination.
- Extremely low false positives rates reduce the incidence of false alarms giving greater confidence to operations, reduced uncertainty and unnecessary expense.
- Minimises evening and weekend work.
- Up to 15-month shelf life at room temperature.
- Can be used for presence/absence (P/A) or quantification testing with Quanti-Tray® and Quanti-Tray®/2000.
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