Simultaneous Determination of Lithium, Sodium, and Calcium in Lithium Carbonate

Application Note 1090: IC Assay for Lithium, Sodium, and Calcium in Lithium Carbonatedemonstrates accurate determinations of these three analytes by separation on a cation-exchange column and detection by suppressed conductivity. This approach offers a fast (25 minutes), simple, accurate, and robust alternative to the time-consuming assays for these three analytes in the current United States Pharmacopeia (USP) monograph.

Lithium carbonate is used to treat a number of mental health problems associated with chemical imbalance in the brain, particularly bipolar disorder. Because lithium is the key ingredient and sodium and calcium are possible cationic impurities in lithium carbonate preparations, the USP requires determination of these compounds. The assays for lithium, sodium, and calcium described in the current USP monograph are cumbersome procedures that use hazardous reagents. This single procedure to determine these three analytes was developed in response to the USP’s global initiative to modernize many of its existing monographs.