Comparison of Serum Lithium Determinations by Flame Photometry and Atomic Absorption Spectrophotometry

Abstract

Abstract Lithium determinations by flame photometry and atomic absorption spec-trophotometry are compared with respect to precision, sensitivity, and the effects of the presence of various concentrations of proteins and cations. Flame photometry gave results closely similar to those obtained by atomic absorption; under the conditions we used, it is more sensitive, slightly less precise, but easier to use. Varying the protein, Na, and K concentrations produces small but demonstrable effects, insignificant for clinical applica-tions. No protein effect was found with flame photometry, in contrast to atomic absorption spectrophotometry, for which protein standards are recommended. Sera from 65 patients receiving lithium therapy were an-alyzed on both instruments; no significant differences were found.