Packaging and storage—
Preserve in tight containers.
Identification—
When moistened with hydrochloric acid, it imparts an intense crimson color to a nonluminous flame.
Water, Method III 
921
—
Dry it at 135
at a pressure not exceeding 5 mm of mercury for 1 hour: it loses between 41.0% and 43.5% of its weight.
Carbonate—
[NOTE—While pipeting and during the subsequent titrations, keep the contents of the flasks blanketed with a stream of carbon dioxide-free air.
] To the flask containing the completed
Final titration obtained in the
Assay add 1 drop of
methyl orange TS, and titrate with 0.1 N hydrochloric acid VS until a persistent orange color is produced and no undissolved barium carbonate remains. Perform a blank titration to determine the volume of 0.1 N hydrochloric acid consumed in going from the phenolphthalein endpoint to the methyl orange endpoint. To 100 mL of carbon dioxide-free water in a 250-mL conical flask add 3 drops of the
Assay preparation, 20 mL of 1 N barium chloride, and 3 drops of
phenolphthalein TS, and allow to stand for 2 minutes. Titrate this solution with 0.1 N hydrochloric acid. At the discharge of the pink color of the indicator, add 1 drop of
methyl orange TS, and titrate with 0.1 N hydrochloric acid VS until a persistent orange color is produced. The titration shows no more CO
2 than corresponds to 1.5 mL of 0.10 N hydrochloric acid (0.7%).
Sulfate 221—
A 2.0-g portion shows no more sulfate than corresponds to 1.0 mL of 0.020 N sulfuric acid (0.05%).
Calcium—
Dissolve 3.33 g in 50 mL of 3 N hydrochloric acid, and proceed as directed in the test for
Calcium under
Lithium Carbonate, beginning with “Boil the clear solution.” Not more than 3.34 mL of 0.10 N potassium permanganate is consumed (0.20%).
Heavy metals, Method I 231—
Dissolve 1.0 g in 15 mL of 3 N hydrochloric acid, and dilute with water to 25 mL: the limit is 0.002%.
Organic volatile impurities, Method V 467:
meets the requirements.
Solvent:
dimethyl sulfoxide.
Lithium content—
Test preparation—
Transfer about 400 mg of Lithium Hydroxide, accurately weighed, to a 1000-mL volumetric flask. Dissolve in and dilute with water to volume, and mix. Pipet 20 mL of this solution into a 1000-mL volumetric flask, add about 950 mL of water, 2 mL of 1 N hydrochloric acid, and 20 mL of a surfactant solution, and mix. Adjust with 1 N hydrochloric acid or 1 N sodium hydroxide to the same pH (±0.1 pH unit) as that of the Standard preparation, dilute with water to volume, and mix.
Procedure—
Employ a suitable flame photometer, and adjust the instrument with the surfactant solution. Aspirate into the instrument the
Standard preparation and the
Assay preparation, and measure the emission at about 671 nm. Calculate the quantity, in mg, of Li in the portion of Lithium Hydroxide taken by the formula:
(13.88 / 73.89)(50C)(A / S),
in which 13.88 is twice the atomic weight of lithium, 73.89 is the molecular weight of lithium carbonate;
C is the concentration, in µg per mL, of
USP Lithium Carbonate RS in the
Standard preparation; and
A and
S are the photometric readings of the
Assay preparation and the
Standard preparation, respectively. The lithium content is between 28.4% and 29.1%, calculated on the anhydrous basis.
Assay—
Assay preparation—
Transfer an accurately weighed quantity of Lithium Hydroxide equivalent to about 10 g of anhydrous lithium hydroxide, to a 1000-mL volumetric flask, dissolve in and dilute with carbon dioxide-free water to volume, and mix.
Preliminary titration—
Pipet 50 mL of the
Assay preparation into a 250-mL conical flask. Start the titration by adding 35 mL of 0.5 N hydrochloric acid VS with continuous vigorous stirring. Add 20 mL of 1 N barium chloride and 3 drops of
phenolphthalein TS, mix, and allow to stand for 2 minutes. Continue the titration with 0.5 N hydrochloric acid VS, and at the discharge of the pink color of the indicator, record the volume of acid solution consumed.
Final titration—
Pipet 50 mL of the
Assay preparation into a 250-mL conical flask.
[NOTE—While pipeting and during the subsequent titrations, keep the contents of the flask blanketed with a stream of carbon dioxide-free air.
] Start the titration by adding with continuous vigorous swirling a volume of 0.5 N hydrochloric acid VS that is 0.50 mL less than that consumed in the preliminary titration. Add 20 mL of 1 N barium chloride and 3 drops of
phenolphthalein TS, mix, and allow to stand for 2 minutes. Rinse the sides of the flask with carbon dioxide-free water, and continue the titration with 0.1 N hydrochloric acid VS. At the discharge of the pink color of the indicator, record the volume of acid solution consumed. Each mL of 0.5 N and 0.1 N hydrochloric acid is equivalent to 11.975 and 2.395 mg of total alkali, respectively, calculated as LiOH.
