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.

Cardiovascular Diseases ; prevention & control ; Humans ; Thioredoxins

A modification of Watkinson's method was used for the flaorimetric determination of selenium in blood, hair, urine and animal tissues with 2,3-Di-aminonaphthalene. A mixture of sulphuric, perchloric acid and sodium molybdate was used for digestion. As little as 3 ng selenium in the sample could be estimated out. Coefficients of variation and recoveries for blood, hair, urine and animal tissues were 3.9, 5.5, 3.3 and 5.6%, and 97.0, 95.0, 97.8 and 99.8% respectively. No significant difference in selenium content estimated was found as graded amounts of samples were taken for analysis, indicating no foreign interference in the extracts. Both precision and accuracy of this method are satisfactory.

2,3-Diaminonaphthalene was used for the fluorometric determination of selenium in cereals and vegetables. Nitric-perchloric-sulphuric acids mixture was used for digestion. Coefficient of variation and recovery for cereals were 4-10% and 97.1%, and for vegetables were 4-18% and 97.8% respectively. Addition of hydrochloric acid to the final digests could be omitted for ordinary cereals and soybean, but it was necessary for samples from seleni-ferous area and some vegetables with higher selenium content such as mushrooms.