Determination of selenium in food supplements by differential-pulse cathodic stripping voltammetry in the presence of added copper.
Selenium was determined by cathodic stripping voltammetry in a 1 mol l-1 HCl acid solution containing added CuII. In this medium, selenium was preconcentrated on the hanging mercury drop electrode and stripped cathodically in differential-pulse mode. After a deposition period of 1 min, 0.2 ng ml-1 of selenium could be detected. The method was applied to the analysis of food supplements. Total selenium was determined after digestion of the sample with HNO3-HClO4 and reduction to the electroactive SeIV by heating with HCl. Inorganic selenium (i.e., selenite and selenate) was similarly determined after extraction with dilute sodium hydroxide solution and clean-up on activated carbon. Representative over-the-counter preparations have been analysed.
Holak
W
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US Food and Drug Administration, Brooklyn, New York 11232.
Specchio
J J
JJ
D003300:Copper; D005527:Food, Fortified / Q000032:analysis*; D007202:Indicators and Reagents; D008903:Minerals; D011048:Polarography / Q000379:methods; D012643:Selenium / Q000032:analysis*; D012680:Sensitivity and Specificity; D013607:Tablets; D014815:Vitamins
D007202:Indicators and Reagents; D008903:Minerals; D013607:Tablets; D014815:Vitamins; D003300:Copper; D012643:Selenium