Packaging and storage—
Preserve in well-closed containers.
Identification—
A:
It effervesces upon the addition of an acid, yielding a colorless gas which, when passed into
calcium hydroxide TS, immediately causes a white precipitate to form.
B:
When moistened with hydrochloric acid, it imparts an intense crimson color to a nonluminous flame.
Reaction—
A saturated solution is alkaline to litmus.
Insoluble substances—
Transfer 10 g to a 250-mL beaker, add 50 mL of water, then add slowly 50 mL of 6 N hydrochloric acid. Cover with a watch glass, and boil the solution for 1 hour. Filter the solution through a dried, tared filtering crucible fitted with a glass-fiber filter disk, using suction. Wash the filter with hot water until the last washing is free from chloride when tested with
silver nitrate TS. Dry the crucible in an oven at 110
for 1 hour: the weight of the residue is not more than 0.02% of the weight of Lithium Carbonate taken.
Chloride 
221
—
To 500 mg of it add 1.2 mL of nitric acid, dilute with water to 50 mL, and add 1 mL of
silver nitrate TS: any turbidity formed is not greater than that produced in a similarly treated control solution containing 0.50 mL of 0.020 N hydrochloric acid (0.07%).
Sulfate 221—
Dissolve 1.0 g in 10 mL of 3 N hydrochloric acid, dilute with water to 40 mL, and add 1 mL of
barium chloride TS. Prepare a standard solution of equal volume containing 1.0 mL of 0.020 N sulfuric acid, 1 mL of 3 N hydrochloric acid, and 1 mL of
barium chloride TS. The turbidity produced in the test solution, after 3 minutes, is not greater than that produced in the standard solution (0.1%).
Aluminum and iron—
Dissolve 500 mg in 10 mL of water by the dropwise addition, with agitation, of hydrochloric acid. Boil the solution, then cool it, and to 5 mL of the solution add 6 N ammonium hydroxide until the reaction is alkaline: no turbidity or precipitate is observed.
Calcium—
Suspend 5.0 g in 50 mL of water, and add a slight excess of 3 N hydrochloric acid. Boil the clear solution to expel carbon dioxide, add 5 mL of
ammonium oxalate TS, render alkaline with 6 N ammonium hydroxide, and allow to stand for 4 hours. Filter through a filtering crucible, and wash with warm water until the last washing yields no turbidity with
calcium chloride TS. Place the crucible in a beaker, cover it with water, add 3 mL of sulfuric acid, heat to 70
, and titrate with 0.10 N potassium permanganate to a pale pink color that persists for 30 seconds. Not more than 3.76 mL of 0.10 N potassium permanganate is consumed (0.15%).
Sodium—
Standard preparation—
Dissolve 1.271 g of sodium chloride, previously dried at 130
to constant weight, in water in a 1000-mL volumetric flask, dilute with water to volume, and mix. Each mL contains 500 µg of Na.
Stock solution—
Suspend 20.0 g of Lithium Carbonate in 100 mL of water, cautiously add 50.0 mL of hydrochloric acid, transfer to a 200-mL volumetric flask, dilute with water to volume, and mix.
Test preparation—
Pipet 5 mL of Stock solution into a 100-mL volumetric flask, add water to volume, and mix.
Control solution—
Pipet 5 mL of Stock solution and 1 mL of Standard preparation into a 100-mL volumetric flask, add water to volume, and mix.
Procedure—
Set a suitable flame photometer for maximum emission at about 589 nm, using the Control solution. Measure the emission intensities of the Test preparation at 580 nm and 589 nm. The difference between the intensities observed at 580 nm and 589 nm for the Test preparation does not exceed the difference between the intensities observed at 589 nm for the Test preparation and the Control solution, respectively. The sodium limit is 0.1%.
Heavy metals 231—
Dissolve 1 g in 10 mL of 3 N hydrochloric acid, and dilute with water to 25 mL: the limit is 0.002%.
Organic volatile impurities, Method I 467:
meets the requirements.
Assay—
Dissolve about 1 g of Lithium Carbonate, accurately weighed, in 50.0 mL of 1 N sulfuric acid VS, add
methyl orange TS, and titrate the excess acid with 1 N sodium hydroxide VS. Perform a blank determination (see
Residual Titrations under
Titrimetry 541). Each mL of 1 N sulfuric acid is equivalent to 36.95 mg of Li
2CO
3.
