SPECTROPHOTOMETRIC METHOD FOR SELENIUM DETERMINATION

摘要

The invention relates to a spectrophotometric method for the determination of selenium in the spiruline biomass, applicable to surveying the biotechnological processes of obtaining proteins or other biologically active substances, or in samples required in some processes in glass industry. After having been cooled at the room temperature, an aqueous solution resulting from the acidic/ alkaline decomposition of a sample is brought to a pH=3, by adding a sodium hydroxide buffer solution in a concentration of 10 %, stabilizing the pH at a value equal to 2.5 ... 3 with a buffer solution comprising citric acid and sodium citrate 0.1 M in citrate anions. The existing cations except for the selenium are extracted from the aqueous phase by jar-ramming in the presence of an antioxidant, and the selenium-containing aqueous solution is acidified with hydrochloric acid in concentration of 37 % when the pH value becomes zero. The antioxidant used is 5. 10 - 5 M carbon tetrachloride dithizon solution, with 2, 6- ditertbutyl, 4-methylphenol in concentration of 0.2 % having the role of solubilizing agent for calcium tetrachloride dithizon.