The measurement of lithium in biologic samples by atomic absorption spectrophotometry

The atomic absorption spectrophotometric method for the measurement of lithium in biologic samples is evaluated. The preparation of standards for measurement of serum and urinary lithium concentrations is provided with discussionof some inter-fering substances. L ITITIUM CARBONATE has become an increasingly important substance in the treatment of manic-depressive psychosis (1). The action of this alkali metal in the affective disorders has led to new areas of biologic research (2). A variety of technics have evolved to measure lithium in biologic samples. Flame photometry is the most sensitive method, and various technical and procedural problems have been discussed in the literature (3-5). In recent years atomic absorption spectrophotometry (AAS) has been utilized, in biologic specimens, to measure ions not readily de-tectable by flame photometry. The measurement of lithium by AAS has recently been discussed (6). However, there is to date no published method for the clinical chemist that includes a discussion of the prob-lems encountered with biologic samples. The purpose of this report is to discuss the results of such an investi-gation and to compare some of these findings with those of flame photometry