Determination of lithium in rat brain regions and synaptosomes by graphite furnace atomic absorption spectrophotometry.

A graphite furnace atomic absorption spectrophotometric method for the analysis of very low concentrations of lithium in brain tissue and subcellular fractions is described. The method has a picogram sensitivity and shows a precision value of 10.1% expressed as the per cent variation coefficient for the tissue analysis of the metal. Lithium concentration in eight regions of the rat brain and regional synaptosomal lithium contents were analyzed with the method described. Results from these determinations show that lithium is heterogeneously distributed among rat brain regions 24 hr after a single s.c. lithium administration; hypothalamus, corpus striatum and midbrain were the regions with the highest lithium accumulation. Lithium is homogeneously concentrated in the synaptosomes obtained from rat brain regions. The method proposed may be considered adequate for trace lithium analysis in pharmacological studies of the metal.