Abstract
The losses of elements in marine biological samples during dry ashing were evaluated on 34 elements by neutron activation analysis. Following biological samples were employed : Eisenia bicyclis (phaeophyceae), Sargassum tortile (phaeophyceae), Zostera marina (phanerogamae), small dried sardines (marine fish), and leaves of Crinum asiaticum (angiospermae). Before ashing, samples were freeze-crushed with liquid nitrogen, These samples were ashed at 100 °C in low temperature plasma ashing and at 500 °C in high temperature ashing. Both the dried and the ashed samples were irradiated simultaniously by thermal neutrons of a KUR reactor for activation analysis. Radioactivity measurements were carried out with a 63 cm3 well type Ge (Li) detector and a Canberra-2048 channel pulse-height analyser over one year after the irradiation. Chlorine, arsenic, selenium, bromine, iodine, gold, and mercury were obviously lost during high temperature ashing. Low temperature plasma ashing was effective for reducing the losses of arsenic and selenium. Depending on the kind of biological samples, there were remarkable differences in losses of halouen elements.
