Determination of lithium in human serum by electrothermal atomic absorption spectrometry

An efficient method was developed for the determination of nanogram levels of lithium in biological samples. Serum samples from human subjects from so utheastern Spain, treated or not treated with lithium carbonate, were analy zed by electrothermal atomic absorption spectrometry. The samples were prev iously treated with a matrix modifier consisting of 0.1% Triton X-100 and i njected through a graphite tube with L'vov platform. The Li concentrations measured by the procedure described for the 3 certified reference samples u sed were not significantly different (p > 0.05) than certified levels. Samp le recoveries and variability during several days, with coefficients of var iation from 4.00 to 14.8%, demonstrated the reliability and accuracy of thi s technique. Mean Li concentration determined in the serum of individuals w ith psychiatric disorders treated with Li (n = 117, 5.077 +/- 1.795 mu g Li /mL) was significantly higher (p < 0.001) than that in individuals not trea ted with Li (n = 24, 1.902 +/- 2.054 ng Li/mL),