Dithiocarbamate extraction of trace amounts of selenium from biological samples for neutron activation analysis

A three-step method has been developed for extracting trace amounts of selenium from biological samples for neutron activation analysis /NAA/. After acid digestion, the sample is first extracted with lead diethyldithiocarbamate at pH 4 to remove a number of interfering elements. Next, selenium is extracted with sodium diethyldithiocarbamate into chloroform at pH 1.5. Finally, selenium is back-extracted with concentrated nitric acid for NAA. Analysis of selenium extracted from four standard reference materials resulted in excellent agreement with the certified values of selenium concentration. A detection limit of 0.05 g has been achieved.