Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

8.2.2 N-(1-Naphthyl)-ethylenediamine Di-hydrochloride (NEDA) - A 1% aqueous
solution should have only one absorption peak at 320 nm over the range of 260-
400 nm. NEDA showing more than one absorption peak over this range is
impure and should not be used.
8.2.3 Hydrogen Peroxide, 30%.
8.2.4 Phosphoric Acid, 85%.
8.2.5 Sulfanilamide Solution - Dissolve 20 g of sulfanilamide in 700 ml of distilled
water. Add, with mixing, 50 ml of 85% phosphoric acid and dilute to 1,000 ml.
This solution is stable for one month, if refrigerated.
8.2.6 NEDA Solution - Dissolve 0.5 g of NEDA in 500 ml of distilled water. This
solution is stable for one month, if refrigerated and protected from light.
8.2.7 Hydrogen Peroxide Solution - Dilute 0.2 ml of 30% hydrogen peroxide to 250
ml with distilled water. This solution may be used for one month, if, refrigerated
and protected from light.
9.0 PROCEDURE
9.1 Preparation of Calibration Graph
9.1.1 Sodium Nitrite - Assay of 97% NaNO2 or greater.
9.1.2 Sodium Nitrite Stock Solution (1000 µg NO - 2/ml) - Dissolve 1.5 g of desiccated
sodium nitrite in distilled water and dilute to 1,000 ml such that a solution
containing 1000 µg NO - 2/ml is obtained. The amount of NaNO2 to be used if, the
assay percent is less than 100%, is calculated as follows :
1.500
G = --------
A
Where :
G = Amount of NaNO2, grams
1.500 = Gravimetric conversion factor
A = Assay, percent (should be 97 or greater)
This stock solution can be stored for six weeks, if refrigerated.
9.1.3 Sodium Nitrite Working Standard (1.0 µg NO - 2/ml)
9.1.3.1 Solution A - Pipet 5 ml of the stock solution into a 500 ml volumetric flask
and dilute to volume with distilled water. This contains 10 µg NO - 2/ml.
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