生物样品、水及土壤中痕量硒的荧光测定法 三、水和土壤中痕量硒的荧光测定法

本文采用2,3-二氨基萘荧光法测定土壤中总硒、水溶性硒和饮水中总硒、四价及六价硒的含量。准确测定含硒量达0.1ppm的土壤,只需0.2g样品;含硒量1ppb的水样只需20ml样品。测定土壤总硒含量范围为59—159ppb时变异系数为12％,回收率为92±6％。水样硒含量范围为2.4—27.9ppb时变异系数为4.3—5.8％,回收率为98±2％。一般天然水中有机物含量不高时,可用消化后加HCl和不加HCl的方法分别测定Se~(4+)及Se~(6+)含量。不同地区的天然饮用水中含硒形式不同,有些水样主要含Se~(4+),有些水样主要含Se~(6+),因此在测定水样总硒含量时,样品消化后必需用HCI还原。

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

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.