Lithium Carbonate Tablets
»Lithium Carbonate Tablets contain not less than 95.0percent and not more than 105.0percent of the labeled amount of Li2CO3.
Packaging and storage— Preserve in well-closed containers.
Identification— Aportion of the powdered Tablets responds to the Identificationtests under Lithium Carbonate.
Dissolution á711ñ
Medium: water;900mL.
Apparatus 1: 100rpm.
Time: 30minutes.
Procedure— Determine the amount in solution by flame photometry,the test specimen being prepared by diluting the 900mLof the solution under test to 1000mLand a 20.0-mLfiltered aliquot being transferred to a 1000-mLvolumetric flask and treated with 500mLof water,1drop of hydrochloric acid,and 20mLof a suitable surfactant solution,appropriately diluted.Add water to volume,mix,and read on a suitable photometer together with the Standard preparationas directed in the Assayunder Lithium Carbonate Capsules.
Tolerances— Not less than 80%(Q)of the labeled amount of Li2CO3is dissolved in 30minutes.
Uniformity of dosage units á905ñ: meet the requirements.
Assay—
Standard preparation— Prepare as directed in the Assayunder Lithium Carbonate Capsules.
Assay preparation— Weigh and finely powder not less than 20Tablets.Weigh accurately a portion of the powder,equivalent to about 600mg of lithium carbonate,and transfer to a 1000-mLvolumetric flask.Add 40mLof water and 5mLof hydrochloric acid,shake until the solid is well disintegrated,dilute with water to volume,and mix.Pipet 10mLof the resulting solution into a 1000-mLvolumetric flask,add about 800mLof water and 20mLof the surfactant solution,dilute with water to volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Lithium Carbonate Capsules.Calculate the quantity,in mg,of Li2CO3in the portion of Tablets taken by the formula:
100C(A/S),
in which Cis the concentration,in µg per mL,of USP Lithium Carbonate RSin the Standard preparation,and Aand Sare the photometer readings of the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 1142
Phone Number:1-301-816-8330