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Prepared at the 46th JECFA (1996), published in FNP 52 Add 4 (1996) superseding specifications prepared at the 19 th JECFA (1975), published in NMRS 55B (1976) and in FNP 52 (1992) under the name Ammonium Hydroxide |
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SYNONYMS |
Ammonium hydroxide, strong ammonia solution, aqueous ammonia, INS No. 527 |
DEFINITION | |
Chemical names |
Ammonia solution |
C.A.S. number |
7664-41-7 (ammonia) 1336-21-6 (aqueous ammonia) |
Chemical formula |
NH3 (aqueous) |
Formula weight |
17.03 |
Assay |
Not less than 27% and not more than 30% |
DESCRIPTION |
Clear, colourless liquid having an exceedingly pungent, characteristic odour. Upon exposure to air it loses ammonia rapidly |
FUNCTIONAL USES |
Acidity regulator |
CHARACTERISTICS | |
IDENTIFICATION | |
Test for ammonia |
Hold a glass rod, wet with hydrochloric acid, near the sample. Dense white fumes are produced. |
Specific gravity |
d (25,25): about 0.90 |
PURITY | |
Non-volatile residue |
Not more than 0.02% by the following procedure: Evaporate 11 ml (10 g) of the sample in a tared platinum or porcelain dish to dryness, dry at 105o for 1 h, cool and weigh |
Readily oxidizable substances |
Dilute 4 ml of the sample with 6 ml of water, and add a slight excess of dilute sulfuric acid TS and 0.1 ml of 0.1N potassium permanganate. The pink colour does not completely disappear within 10 min. |
Heavy metals |
Not more than 5 mg/kg Transfer 22 ml (20 g of the sample) to a beaker, add about 5 mg of sodium chloride, evaporate to dryness on a steam bath, and dissolve the residue in 2 ml of dilute acetic acid TS and sufficient water to make 50 ml. A 10-ml portion of this solution, diluted to 25 ml with water, meets the requirements of the Limit Test (Method I). |
METHOD OF ASSAY |
Tare accurately a 125-ml glass-stoppered conical flask containing 35.0 ml of 1N sulfuric acid. Cool the sample in the original bottle to 10o or lower. Partially fill a 10-ml graduated pipet from near the bottom (do not use vacuum for drawing up the sample). Wipe off any liquid adhering to the outside of the pipet and discard the first ml. Hold the pipet just above the surface of the acid and transfer 2 ml into the flask, leaving at least 1 ml in the pipet. Stopper the flask, mix and weigh again to obtain the weight of the sample. Add methyl red TS and titrate the excess acid with 1N sodium hydroxide. Subtract the excess sulfuric acid from the total sulfuric acid (35.0 ml) to find the ml used to neutralize the sample. Each ml of 1N sulfuric acid used to neutralize the ammonia is equivalent to 17.03 mg of NH3. |