(lith' ee um hye drox' ide).
Lithium hydroxide monohydrate.
Lithium hydroxide monohydrate [1310-66-3].
Anhydrous 23.95 [1310-65-2].
» Lithium Hydroxide contains not less than 98.0 percent and not more than 102.0 percent of LiOH, calculated on the anhydrous basis.
[CautionExercise great care in handling Lithium Hydroxide, as it rapidly destroys tissues. ]
Packaging and storage Preserve in tight containers.
USP Reference standards 11
USP Lithium Carbonate RS
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 [noteWhile 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 CO2 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%.
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 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. [noteWhile 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.
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