(Sodium Hydrogen Carbonate, Ph. Eur. monograph 0195)
NaHCO3 84.0 144-55-8
Action and use
Antacid; used in treatment of electrolyte deficiency.
Preparations
Sodium Bicarbonate Ear Drops
Sodium Bicarbonate Eye Lotion
Sodium Bicarbonate Infusion
Sodium Bicarbonate Oral Solution
Compound Sodium Bicarbonate Tablets
DEFINITION
Content
99.0 per cent to 101.0 per cent.
CHARACTERS
Appearance
White or almost white, crystalline powder.
Solubility
Soluble in water, practically insoluble in ethanol (96 per cent).
When heated in the dry state or in solution, it gradually changes into sodium carbonate.
IDENTIFICATION
A. To 5 mL of solution S (see Tests) add 0.1 mL of phenolphthalein solution R. A pale pink colour is produced. Heat; gas is evolved and the solution becomes red.
B. It gives the reaction of carbonates and bicarbonates (2.3.1).
C. Solution S gives reaction (a) of sodium (2.3.1).
TESTS
Solution S
Dissolve 5.0 g in 90 mL of carbon dioxide-free water R and dilute to 100.0 mL with the same solvent.
Appearance of solution
Solution S is clear (2.2.1) and colourless (2.2.2, Method II).
Carbonates
The pH (2.2.3) of freshly prepared solution S is not greater than 8.6.
Chlorides (2.4.4)
Maximum 150 ppm.
To 7 mL of solution S add 2 mL of nitric acid R and dilute to 15 mL with water R.
Sulfates (2.4.13)
Maximum 150 ppm.
To a suspension of 1.0 g in 10 mL of distilled water R add hydrochloric acid R until neutral and about 1 mL in excess. Dilute to 15 mL with distilled water R.
Ammonium (2.4.1)
Maximum 20 ppm.
Dilute 10 mL of solution S to 15 mL with water R. Prepare the standard using a mixture of 5 mL of water R and 10 mL of ammonium standard solution (1 ppm NH4) R.
Calcium (2.4.3)
Maximum 100 ppm.
To a suspension of 1.0 g in 10 mL of distilled water R add hydrochloric acid R until neutral and dilute to 15 mL with distilled water R.
Iron (2.4.9)
Maximum 20 ppm.
Dissolve 0.5 g in 5 mL of dilute hydrochloric acid R and dilute to 10 mL with water R.
ASSAY
Dissolve 0.750 g in 50 mL of carbon dioxide-free water R. Titrate with 1 M hydrochloric acid, determining the end-point potentiometrically (2.2.20). Read the volume added at the 2 point of inflection, or at the point of inflection if only 1 point is detected.
1 mL of 1 M hydrochloric acid is equivalent to 84.0 mg of NaHCO3.
