Automated determination of traces of mercury in biological materials by substoichiometric radioisotope dilution.
Solid samples (1-2 g) are burned in oxygen in a flask containing radiomercury in dilute hydrochloric acid, in which the non-active mercury to be determined is immediately absorbed. All mercury is subsequently extracted by dithizone in carbon tetrachloride and then re-extracted into dilute hydrochloric acid. This aqueous phase is further analysed automatically (AutoAnalyzer, 20 samples hr ) as previously described. Liquids (up to 100 ml) are analysed in the same way but instead of being burned in oxygen are first oxidized with potassium permanganate in acid medium. Quantities between 2 and 0.00004 ppm Hg were determined in various materials. Results for international biological standards agreed well with values obtained by activation analysis: kale 0.159 ppm Hg (relative standard deviation 2%) and IAEA cereals 0.0435 ppm Hg (+/- 5%). The new method is far more simple and rapid than activation analysis and just as sensitive; it is therefore more suitable for routine work. About 100 samples can be analysed per day.
Růzicka
J
J
Chemistry Department A, Technical University of Denmark, Building 207, Lyngby, Denmark.
Lamm
C G
CG