Procedure 1
Prepare a dense “milky” suspension (at least McFarland No. 4) from the strain to be tested in 0.25 ml saline in a tube. Add one Nitrate Reduction tablet and close the tube. Incubate at 35-37 °C for 4 hours or 18-24 hours.
After incubation add 1 drop of N,N-Dimethyl-α-Naphthylamine sol. (Nitrate B Reagent) and 1 drop Sulfanilic acid sol. (Nitrate A Reagent). Read within 2 minutes.
Reading of the test
Positive reaction: Red/pink
Negative reaction: Colourless, light pink
Procedure 2
When testing anaerobes, the tablet can also be placed on an inoculated plate, which is incubated for 24-48 hours.
After incubation 1 drop each of N,N-Dimethyl-α-Naphthylamine sol. (Nitrate B Reagent) and Sulfanilic acid sol. (Nitrate A Reagent) is added to the tablet.
Reading of the test
A pink or red colour is interpreted as positive indicating reduction of nitrate to nitrite.
