Product properties

• Appearance: white or light-yellow granules
• Clarity: colorless or slightly yellow
• pH: 7.0–7.6
• Weight: 2.7 ±0.5 g
• Storage: refrigerate, keep dry and sealed, and protect from light at 4–8°C
• Shelf life: 1 year
• Packaging: 200 tests per box

Working principle

Total coliforms produce beta-galactosidase, which decomposes the ONPG chromogenic substrate and turns the medium yellow. E. coli produces beta-glucuronidase, which decomposes the MUG fluorescent substrate and produces characteristic fluorescence under 366 nm ultraviolet light. Thermotolerant coliforms produce a yellow reaction when incubated with ONPG at approximately 44.5°C.

Qualitative detection

1. Add reagent to a 100 mL water sample, dissolve, and incubate for 24 hours at 36 ±1°C.
2. Read the result: colorless is negative; yellow indicates total coliform positive; yellow with fluorescence indicates E. coli positive.

Quantitative detection

1. Dissolve reagent in a 100 mL water sample.
2. Pour into a 51- or 97-well detection tray and seal with an LK sealer.
3. Incubate for 24 hours at 36°C, or at 44.5 ±0.5°C for thermotolerant coliforms.
4. Count positive wells and consult the corresponding MPN table.