Lithium Carbonate
Li2CO3 73.89

Carbonic acid,dilithium salt.
Dilithium carbonate [554-13-2].
»Lithium Carbonate contains not less than 99.0percent of Li2CO3,calculated on the dried basis.
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— Asaturated solution is alkaline to litmus.
Loss on drying á731ñ— Dry it at 200for 4hours:it loses not more than 1.0%of its weight.
Insoluble substances— Transfer 10g to a 250-mLbeaker,add 50mLof water,then add slowly 50mLof 6Nhydrochloric acid.Cover with a watch glass,and boil the solution for 1hour.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 110for 1hour:the weight of the residue is not more than 0.02%of the weight of Lithium Carbonate taken.
Chloride á221ñ— To 500mg of it add 1.2mLof nitric acid,dilute with water to 50mL,and add 1mLof silver nitrate TS:any turbidity formed is not greater than that produced in a similarly treated control solution containing 0.50mLof 0.020Nhydrochloric acid (0.07%).
Sulfate á221ñ— Dissolve 1.0g in 10mLof 3Nhydrochloric acid,dilute with water to 40mL,and add 1mLof barium chloride TS.Prepare a standard solution of equal volume containing 1.0mLof 0.020Nsulfuric acid,1mLof 3Nhydrochloric acid,and 1mLof barium chloride TS.The turbidity produced in the test solution,after 3minutes,is not greater than that produced in the standard solution (0.1%).
Aluminum and iron— Dissolve 500mg in 10mLof water by the dropwise addition,with agitation,of hydrochloric acid.Boil the solution,then cool it,and to 5mLof the solution add 6Nammonium hydroxide until the reaction is alkaline:no turbidity or precipitate is observed.
Calcium— Suspend 5.0g in 50mLof water,and add a slight excess of 3Nhydrochloric acid.Boil the clear solution to expel carbon dioxide,add 5mLof ammonium oxalate TS,render alkaline with 6Nammonium hydroxide,and allow to stand for 4hours.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 3mLof sulfuric acid,heat to 70,and titrate with 0.10Npotassium permanganate to a pale pink color that persists for 30seconds.Not more than 3.76mLof 0.10Npotassium permanganate is consumed (0.15%).
Sodium—
Standard preparation— Dissolve 1.271g of sodium chloride,previously dried at 130to constant weight,in water in a 1000-mLvolumetric flask,dilute with water to volume,and mix.Each mLcontains 500µg of Na.
Stock solution— Suspend 20.0g of Lithium Carbonate in 100mLof water,cautiously add 50.0mLof hydrochloric acid,transfer to a 200-mLvolumetric flask,dilute with water to volume,and mix.
Test preparation— Pipet 5mLof Stock solutioninto a 100-mLvolumetric flask,add water to volume,and mix.
Control solution— Pipet 5mLof Stock solutionand 1mLof Standard preparationinto a 100-mLvolumetric flask,add water to volume,and mix.
Procedure— Set a suitable flame photometer for maximum emission at about 589nm,using the Control solution.Measure the emission intensities of the Test preparationat 580nm and 589nm.The difference between the intensities observed at 580nm and 589nm for the Test preparationdoes not exceed the difference between the intensities observed at 589nm for the Test preparationand the Control solution,respectively.The sodium limit is 0.1%.
Heavy metals á231ñ— Dissolve 1g in 10mLof 3Nhydrochloric acid,and dilute with water to 25mL:the limit is 0.002%.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Assay— Dissolve about 1g of Lithium Carbonate,accurately weighed,in 50.0mLof 1Nsulfuric acid VS,add methyl orange TS,and titrate the excess acid with 1Nsodium hydroxide VS.Perform a blank determination (see Residual Titrationsunder Titrimetry á541ñ).Each mLof 1Nsulfuric acid is equivalent to 36.95mg of Li2CO3.
Auxiliary Information— Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 1141
Phone Number:1-301-816-8330