Lithium Hydroxide
LiOH·H2O 41.96

Lithium hydroxide monohydrate.
Lithium hydroxide monohydrate [1310-66-3].

Anhydrous 23.95 [1310-65-2].
»Lithium Hydroxide contains not less than 98.0percent and not more than 102.0percent of LiOH,calculated on the anhydrous basis.
[Caution—Exercise great care in handling Lithium Hydroxide,as it rapidly destroys tissues. ]
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 IIIá921ñ— Dry it at 135at a pressure not exceeding 5mm of mercury for 1hour: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 titrationobtained in the Assayadd 1drop of methyl orange TS,and titrate with 0.1Nhydrochloric acid VSuntil a persistent orange color is produced and no undissolved barium carbonate remains.Perform a blank titration to determine the volume of 0.1Nhydrochloric acid consumed in going from the phenolphthalein endpoint to the methyl orange endpoint.To 100mLof carbon dioxide-free water in a 250-mLconical flask add 3drops of the Assay preparation,20mLof 1Nbarium chloride,and 3drops of phenolphthalein TS,and allow to stand for 2minutes.Titrate this solution with 0.1Nhydrochloric acid.At the discharge of the pink color of the indicator,add 1drop of methyl orange TS,and titrate with 0.1Nhydrochloric acid VSuntil a persistent orange color is produced.The titration shows no more CO2than corresponds to 1.5mLof 0.10Nhydrochloric acid (0.7%).
Sulfate á221ñ— A2.0-g portion shows no more sulfate than corresponds to 1.0mLof 0.020Nsulfuric acid (0.05%).
Calcium— Dissolve 3.33g in 50mLof 3Nhydrochloric acid,and proceed as directed in the test for Calciumunder Lithium Carbonate,beginning with “Boil the clear solution.”Not more than 3.34mLof 0.10Npotassium permanganate is consumed (0.20%).
Heavy metals,Method Iá231ñ— Dissolve 1.0g in 15mLof 3Nhydrochloric acid,and dilute with water to 25mL:the limit is 0.002%.
Organic volatile impurities,Method Vá467ñ: meets the requirements.
Solvent: dimethyl sulfoxide.
Lithium content—
Standard preparation— Prepare as directed in the Assayunder Lithium Citrate.Determine its pH.
Test preparation— Transfer about 400mg of Lithium Hydroxide,accurately weighed,to a 1000-mLvolumetric flask.Dissolve in and dilute with water to volume,and mix.Pipet 20mLof this solution into a 1000-mLvolumetric flask,add about 950mLof water,2mLof 1Nhydrochloric acid,and 20mLof a surfactant solution,and mix.Adjust with 1Nhydrochloric acid or 1Nsodium hydroxide to the same pH(±0.1pHunit)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 preparationand the Assay preparation,and measure the emission at about 671nm.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 13.88is twice the atomic weight of lithium,73.89is the molecular weight of lithium carbonate,Cis the concentration,in µg per mL,of USP Lithium Carbonate RSin the Standard preparation,and Aand Sare the photometric readings of the Assay preparationand 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 10g of anhydrous lithium hydroxide,to a 1000-mLvolumetric flask,dissolve in and dilute with carbon dioxide-free water to volume,and mix.
Preliminary titration— Pipet 50mLof the Assay preparationinto a 250-mLconical flask.Start the titration by adding 35mLof 0.5Nhydrochloric acid VSwith continuous vigorous stirring.Add 20mLof 1Nbarium chloride and 3drops of phenolphthalein TS,mix,and allow to stand for 2minutes.Continue the titration with 0.5Nhydrochloric acid VS,and at the discharge of the pink color of the indicator,record the volume of acid solution consumed.
Final titration— Pipet 50mLof the Assay preparationinto a 250-mLconical 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 0.5Nhydrochloric acid VSthat is 0.50mLless than that consumed in the preliminary titration.Add 20mLof 1Nbarium chloride and 3drops of phenolphthalein TS,mix,and allow to stand for 2minutes.Rinse the sides of the flask with carbon dioxide-free water,and continue the titration with 0.1Nhydrochloric acid VS.At the discharge of the pink color of the indicator,record the volume of acid solution consumed.Each mLof 0.5Nand 0.1Nhydrochloric acid is equivalent to 11.975and 2.395mg of total alkali,respectively,calculated as LiOH.
Auxiliary Information— Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 1144
Phone Number:1-301-816-8330