Sodium nitrite, with chemical formula NaNO2, is used as a color fixative and preservative in meats and fish. When pure, it is a white to slight yellowish crystalline powder. It is very soluble in water and is hygroscopic. It is also slowly oxidized by oxygen in the air to sodium nitrate, NaNO3. The compound is a strong oxidizing agent.
It is also used in manufacturing diazo dyes, nitroso compounds, and other organic compounds; in dyeing and printing textile fabrics and bleaching fibers; in photography; as a laboratory reagent and a corrosion inhibitor; in metal coatings for phosphatizing and detinning; and in the manufacture of rubber chemicals. It may also be used as an electrolyte in electrochemical grinding manufacturing processes, typically diluted to about 10% concentration in water.
Sodium Nitrite Specifications
Tests ------------------------------------------- Limits
Appearance -------------------------------------- White to off-white crystalline
powder
Purity (On dry basis) by KMnO4 titration -------- 99.00 % w/w Min
Loss on drying at 110ºC for 10 min -------------- 0.50 % w/w Max
Alkalinity as Na2CO3 or NaOH by H2SO4 titration - 0.20 % w/w Max
Chloride as Cl by Nitrobenzene ------------------ 0.10 % w/w Max
Sodium Nitrate by PDSA -------------------------- 1.00 % w/w Max
Water insoluble --------------------------------- 0.05 % w/w Max
Sulphate as SO4 by turbidity -------------------- 0.08 % w/w Max
Iron as Fe by Potassium thiocyanate ------------- 0.002 % w/w Max
Heavy metal as Pb by visual colourimetric ------- 0.005 % w/w Max
Clarity of 30% aqueous solution ----------------- It should be clear solution
The material can also be offered with anti-caking agent.
Sodium Nitrite BP Pharmacopoeia
NaNO2
Action and use
Used in treatment of cyanide poisoning.
DEFINITION
Content
98.5 per cent to 100.5 per cent (dried substance).
CHARACTERS
Appearance
Colourless crystals or mass or yellowish rods, hygroscopic.
Solubility
Freely soluble in water, soluble in alcohol.
IDENTIFICATION
A. Dilute 1 ml of solution S1 (see Tests) to 25 ml with water R. To 0.1 ml of the solution add 1 ml of sulphanilic acid solution. Allow to stand for 2-3 min. Add 1 ml of b-naphthol solution and 1 ml of dilute sodium hydroxide solution R. An intense red colour develops.
B. To 1 ml of the solution prepared for identification test A add 3 ml of a 20 g/l solution of phenazone and 0.4 ml of dilute sulphuric acid. An intense green colour develops.
C. To 0.15 ml of solution S1, add 0.35 ml of water R. The solution gives reaction of sodium.
TESTS
Solution S1
Dissolve 2.5 g in carbon dioxide-free water and dilute to 50 ml with the same solvent.
Solution S2
Dissolve 3 g in distilled water. Cautiously add 10 ml of nitric acid and evaporate to dryness. Dissolve the residue in 10 ml of distilled water R, neutralize with dilute sodium hydroxide solution and dilute to 30 ml with distilled water.
Appearance of solution
Solution S1 is clear and not more intensely coloured than reference solution.
Acidity or alkalinity
To 10 ml of solution S1, add 0.05 ml of phenol red solution. Add 0.1 ml of 0.01 M sodium hydroxide. The solution is red. Add 0.3 ml of 0.01 M hydrochloric acid. The solution is yellow.
Chlorides
Maximum 50 ppm.
Dilute 10 ml of solution S2 to 15 ml with water. The solution complies with the limit test for chlorides.
Sulphate
Maximum 200 ppm.
Heavy metals
Maximum 20 ppm.
Loss on drying
Maximum 1.0 per cent, determined on 1.000 g by drying in vacuum.
NaNO2 69.00
Nitrous acid, sodium salt.
Sodium nitrite [7632-00-0]
Sodium Nitrite contains not less than 97.0 percent and not more than 101.0 percent of NaNO2, calculated on the dried basis.
Identification— A solution of it responds to the tests for Sodium and for Nitrite.
Loss on drying— Dry it over silica gel for 4 hours: it loses not more than 0.25% of its weight.
Heavy metals— Dissolve 1 g in 6 mL of 3 N hydrochloric acid, and evaporate on a steam bath to dryness. Reduce the residue to a coarse powder, and continue heating on the steam bath until the odor of hydrochloric acid no longer is perceptible. Dissolve the residue in 23 mL of water, and add 2 mL of 1 N acetic acid: the limit is 0.002%.
Assay— Dissolve about 1 g of Sodium Nitrite, accurately weighed, in water to make 100.0 mL. Pipette 10 mL of this solution into a mixture of 50.0 mL of 0.1 N potassium permanganate VS, 100 mL of water, and 5 mL of sulfuric acid. When adding the Sodium Nitrite solution, immerse the tip of the pipette beneath the surface of the permanganate mixture. Warm the liquid to 40 , allow it to stand for 5 minutes, and add 25.0 mL of 0.1 N oxalic acid VS. Heat the mixture to about 80 , and titrate with 0.1 N potassium permanganate VS. Each mL of 0.1 N potassium permanganate is equivalent to 3.450 mg of NaNO2.
NaNO2 Formula wt 69.00
INS: 250 CAS: [7632-00-0]
DESCRIPTION
Sodium Nitrite occurs as a white to slightly yellow, granular powder, or as white or nearly white, opaque, fused masses or sticks. It is hygroscopic in air. Its solutions are alkaline to litmus. One gram dissolves in 1.5 mL of water, but it is sparingly soluble in alcohol.
Function: Color fixative in meat and meat products; antimicrobial agent; preservative.
REQUIREMENTS
Identification: An aqueous solution gives positive tests for Sodium and for Nitrite.
Assay: Not less than 97.0% and not more than 100.5% of NaNO2 after drying.
Lead: Not more than 4 mg/kg.
Loss on Drying: Not more than 0.25%.
Sodium Nitrite
NaNO2
Formula Wt 69.00
CAS Number 7632-00-0
REQUIREMENTS
Assay: 97.0% NaNO2 min
MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Chloride (Cl): 0.005%
Sulfate (SO4): 0.01%
Calcium (Ca): 0.01%
Potassium (K): 0.005%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.001%
