Colitag Presence/Absence Method Training

March 10, 2022

An overview of Neogen®'s Colitag™ presence/absence test for total coliforms and E. coli in water.

Colitag™ is relied upon by water testing laboratories worldwide to help ensure clean, safe water. Colitag is an easy-to-use, presence-absence (P/A) enzyme-substrate test for determining total coliform and E. coli in water samples. Our solution can detect as low as 1 CFU of total coliform and E. coli in a 100 mL water sample.

To use, add Colitag to a 100 mL water sample, incubate and read the color change and UV response in 16–48 hours. Colitag offers the most flexible reading window with a single product, allowing technicians the freedom to choose timing that works best for their schedule.

Neogen® supports water labs in their mission to ensure water is safe in a timely manner.

We offer additional accessories for testing including sample containers and a Comparator. Colitag offers you:

  • Reliable results down to 1 CFU
  • Simple and easy-to-use test
  • Fastest time to results at 16 hours
  • Flexible reading window of 16–48 hours


Video Transcript

Colitag™—Neogen®'s easy-to-use test for total coliform and E. coli with the most flexible reading window.

Step 1—Prior to use, shake the stick pack or tilt back and forth to ensure the media is free flowing.

To open, pull the perforated tear tab away.

Add Colitag to the water sample.

When working with samples that may contain residual chlorine, ensure water is collected in a vessel that contains sodium thiosulfate to neutralize the impact.

Step 2—Incubate for 16–48 hours.

For early reading at 16–24 hours, if the sample is not already at 33–38°C, then place the sample vessel in a water bath at 35°C for 20 minutes or 44.5°C for 7–10 minutes, and then proceed to incubation.

Step 3—After incubation, visually check for coliforms against the comparator or control.

Samples that are more yellow than the comparator are positive for coliforms.

Step 4—Fluorescence check for E. coli by using a 365 nanometer UV light source.

Samples that flouresce more than the comparator are positive for E. coli.

Please contact Neogen with any questions.


Category: Solution Spotlights, Water, Water Treatment