Decomposition of biological materials,rocks and soils with simultaneous volatilization of trace elements in pure oxygen under dynamic conditions

Cadmium, thallium, lead and bismuth are quantitatively liberated from rocks and soils after addition of various additives, by opening out in a stream of pure oxygen in a special combustion apparatus. The elements volatilize as oxides and/or halides and condense on a cold finger, whence they are dissolved with about 2 ml of hydrochloric acid (1 + 1) or nitric acid (65%) by boiling under reflux. Concomitant heavy metals remain in the slug which forms on the sample holder that is removed after combustion. Yield monitoring for cadmium, lead and bismuth was done by using radioactive nuclides and for thallium by a spectrophotometric method (rhodamine B). The recovery rates are over 95% for all matrices studied. Good agreement was found for thallium values with standard reference materials.