Identification—
A:
When diluted with an equal volume of 3Nhydrochloric acid,it imparts an intense crimson color to a nonluminous flame.
B:
It responds to the test for Citrate á191ñ.
Assay—
Standard preparation—
Prepare as directed in the
Assayunder
Lithium Citrate.Determine its pH.
Assay preparation—
Transfer an accurately measured volume of Syrup,equivalent to about 60mg of lithium,to a 1000-mLvolumetric flask,dilute with water to volume,and mix.Pipet 20mLof the resulting 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 photometer the
Standard preparationand the
Assay preparation,and measure the emission at about 671nm.Calculate the quantity,in mg,of lithium in each mLof the Syrup taken by the formula:
(13.88/73.89)(50C/V)(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;Vis the volume,in mL,of Syrup taken;and
Aand
Sare the photometer readings of the
Assay preparationand the
Standard preparation,respectively.