Reagents and Test Media
The following reagents and test media are required for the Modified Griess Test:
- Nitrite sensitive emulsion-coated test paper
- Nitrite test swabs (nitrite compound positive control samples)
- Solution of glacial acetic acid (15%) and distilled or deionized water
- Nitrite compound-free cheesecloth
Nitrite Sensitive Emulsion-Coated Test Paper
Desensitized photographic paper or photographic printer paper can be used as a medium for capturing the azo dye pigment patterns generated during the Modified Griess Test.
The test paper preparation procedure is as follows:
- Prepare a solution of 7.7 grains (.5 grams) of sulfanilic acid in 100 mL of distilled or deionized water.
- Prepare a solution of 4.3 grains (.28 grams) of alpha-naphthol in 100 mL of methanol.
- Combine equal volumes of the above solutions.
- Pour the combined solutions into a nonreactive photo processing tray. Briefly submerge and remove precut sheets of the test paper into the tray.
- Set the sheets aside to dry on an uncontaminated surface or hang to dry.
- Store any unused solution in a sealed container labeled according to laboratory protocol.
- Store dried test paper in a dry place.
Nitrite Test Swabs
- Prepare a solution of 9.3 grains (0.6 grams) of sodium nitrite in 100 mL of distilled or deionized water.
- Soak cotton tipped swabs in the nitrite solution.
- Set the swabs aside to dry.
- Store swabs in a sealed container labeled according to laboratory protocol.
Glacial Acetic Acid
- Combine 150 mL of glacial acetic acid with 850 mL of distilled or deionized water.
- Store the solution in a sealed container labeled according to laboratory protocol.
Cut nitrite-free cheesecloth to the size of the processed test paper. (If the cheesecloth contains nitrites, it may produce an orange background color on the processed test paper.)