Determination of selenium and tin in human brain by graphite furnace atomic absorption spectrometry

A method is reported for measuring Se and Sn in human brain tissue. The patients from whom the samples were taken had no diseases in their central nervous system. Microwave energy was applied to digest the brain samples. The digested samples were analyzed without dilution by transversely heated graphite atomizer for atomic absorption spectrometry with longitudinal Zeeman background correction. The dependence of integrated absorbance on various chemical modifiers has been examined. The most appropriate technique proved to be 5 mul sample injection using 20 mug prereduced palladium-nitrate for Se determination, and 20 W sample injection applying 10 mug palladium-nitrate + 3 mug magnesium-nitrate for the measurements of Sn. The optimal temperature program was found to be 1200 degreesC pyrolysis and 2100 degreesC atomisation temperature for Se and 1500 degreesC pyrolysis and 2300 degreesC atomisation temperature for Sn. Accuracy of the applied techniques was tested by the analysis of standard reference materials. The precision was +/-5% for Se and +/- 10% for Sn. The range of recovery values was 85-95% for Se and 95-105% for Sn. The mean Se concentrations in the investigated brain parts ranged from 200 to 700 ng/g, while the Sn concentrations were between 20 and 300 ug/g dry weight.