Lithium carbonate serves as a mild basic salt in specialized biochemical applications. It is particularly used in lithium ion supplementation studies, nucleic acid stabilization, and pH-sensitive precipitation processes due to its low solubility in water and distinctive carbonate chemistry.

Chemical Properties

Lithium carbonate (Li₂CO₃, molecular weight 73.89 g/mol) appears as a white, odorless crystalline powder with a monoclinic structure (density 2.11 g/cm³, melting point 723°C). Its crystal lattice (space group C₂/c) is characterized by lithium ions coordinated to oxygen atoms from planar carbonate (CO₃²⁻) groups. The compound is poorly soluble in water (approximately 1.3 g/L at 20°C), with solubility significantly increasing under carbon dioxide pressure due to the formation of metastable lithium bicarbonate (LiHCO₃).

In aqueous solution, carbonate ions undergo hydrolysis, leading to alkaline conditions (pH ~11.3 in saturated solutions). At elevated temperatures above 1000°C, lithium carbonate thermally decomposes into lithium oxide (Li₂O) and carbon dioxide (CO₂).

Biochemical Applications

In molecular biology, lithium carbonate is used at concentrations ranging from 10 to 50 mM in TE buffers to stabilize supercoiled plasmid DNA during alkaline lysis, as lithium ions reduce DNA renaturation kinetics compared to sodium ions. In neurochemical research, it is applied at lower concentrations (1–5 mM) to reproduce lithium-mediated inhibition of glycogen synthase kinase-3 beta (GSK-3β) in neuronal cell cultures.

Protein chemistry applications include the use of saturated lithium carbonate suspensions for selective precipitation of γ-carboxyglutamic acid (Gla)-containing proteins, such as prothrombin, under alkaline conditions. Additionally, analytical laboratories exploit its carbon dioxide-dependent solubility behavior for lithium quantification in biological samples, particularly serum, using techniques such as inductively coupled plasma mass spectrometry (ICP-MS) following bicarbonate extraction.