Lithium Carbonate Tablets
DEFINITION
Lithium Carbonate Tablets contain NLT 95.0% and NMT 105.0% of the labeled amount of Li2CO3.
IDENTIFICATION
A portion of the powdered Tablets meets the requirements of the following tests.
• A.
It effervesces upon the addition of an acid, yielding a colorless gas that, 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.
ASSAY
• Procedure
Standard solution:
Transfer 30 mg of USP Lithium Carbonate RS to a 100-mL volumetric flask, and add 20 mL of water and 0.5 mL of hydrochloric acid. Shake until dissolved, and dilute with water to volume. Pipet 20 mL of the resulting solution into a 1000-mL volumetric flask, add 800 mL of water and 20 mL of a suitable surfactant solution, and dilute with water to volume.
Sample solution:
Powder NLT 20 Tablets. Transfer a portion of powder, nominally equivalent to 600 mg of lithium carbonate, into a 1000-mL volumetric flask. Add 40 mL of water and 5 mL of hydrochloric acid, shake until the solid is well disintegrated, and dilute with water to volume. Pipet 10 mL of the resulting solution into a 1000-mL volumetric flask, add 800 mL of water and 20 mL of the surfactant solution, and dilute with water to volume.
Spectrometric conditions
Mode:
Flame photometer
Analytical wavelength:
About 671 nm
[Note—Adjust the instrument with the surfactant solution. ]
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of Li2CO3 in the portion of Tablets taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of the Standard solution (mg/mL) |
| CU | = | = nominal concentration of lithium carbonate in the Sample solution (mg/mL) |
Acceptance criteria:
95.0%–105.0%
PERFORMANCE TESTS
• Dissolution 
711
711
Medium:
Water; 900 mL
Apparatus 1:
100 rpm
Time:
30 min
Surfactant solution:
Nonoxynol-9 in water (1:1) v/v
Standard solution:
Transfer 30 mg of USP Lithium Carbonate RS to a 100-mL volumetric flask. Add 20 mL of water and 0.5 mL of hydrochloric acid, shake until dissolved, and dilute with water to volume. Pipet 20 mL of the resulting solution into a 1000-mL volumetric flask, add 800 mL of water and 20 mL of a suitable surfactant solution, and dilute with water to volume.
Sample solution:
Dilute 900 mL of the solution under test with Medium to 1000 mL. Pass through a suitable filter. Transfer 20.0 mL of the filtrate to a 1000-mL volumetric flask. Add 500 mL of water, 1 drop of hydrochloric acid, and 20 mL of Surfactant solution. Dilute with water to volume.
Analysis
Samples:
Standard solution and Sample solution
Determine the percentage of Li2CO3 dissolved:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Lithium Carbonate RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of the Sample solution (mg/mL) |
Tolerances:
NLT 80% (Q) of the labeled amount of Li2CO3 is dissolved.
• Uniformity of Dosage Units 905:
Meet the requirements
905:
Meet the requirements
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
• USP Reference Standards 11
11
USP Lithium Carbonate RS
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Hariram Ramanathan, M.S.
Associate Scientific Liaison 1-301-816-8313 |
(SM42010) Monographs - Small Molecules 4 |
| 711 |
Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison 1-301-816-8106 |
(GCDF2010) General Chapters - Dosage Forms |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 3700
Pharmacopeial Forum: Volume No. 35(6) Page 1461