METHODS OF FLUORIMETRIC DETERMINATION OF TRACE AMOUNT OF SELENIUM IN BIOLOGICAL MATERIALS, WATER AND SOIL 3. DETERMINATION OF SELENIUM IN WATER AND SOIL / 营养学报

ABSTRACT

Total and water soluble selenium in soil, and total, tetravalent and he-xavalent selenium in drinking water were determined fluorimetrically by 2, 3-diaminonaphthalene. The digestive mixture was composed of sulphuric, perchloric acids and sodium molybdate 0.2 g of soil and 20 ml of water samples were sufficient for analysis when their selenium concentrations were at the level of 0.1 ppm and 1 ppb respectively. Coefficient of variation and recovery for soil was 12% and 92 ?6%, and for water was 4.3-5.8% and 98 ?2% respectively. Tetravalent and hexavalent selenium content could be measured differentially by the addition or omission of hydrochloric acid in ordinary water samples containing only small amounts of organic matter. In addition to tetravalent selenium substantial amounts of hexavalent selenium may occur occasionally in drinking water and it is thus necessary to add hydrochloric acid to the final digests to completely reduce hexavalent selenium to the tetravalent state for the estimation of total selenium in water samples.