May you suggest a method to quantify organic selenium in food?
I thought to express it, as the difference between total selenium and inorganic (water soluble forms), but i'm not sure to extract only inorganic forms!
Thanks in advance
Stefano
Dear Sir. Concerning your issue about the method to quantify organic seleniu, in food. Different analytical methods with different detection limits and accuracy have been proposed. The following below links may help you in your analysis:
http://www.atsdr.cdc.gov/toxprofiles/tp92-c7.pdf
http://www.ijppsjournal.com/Vol5Issue4/7731.pdf
Thanks
It is clear that you want to calculate organic selenium and inorganic selenium. Since polarity of organic selenium is less you can reflux with hexane for couple of hours to extract organic selenium after drying your sample in a vacuum oven. To analyze total selenium you can char the sample in oven and leach with hyrochloric acid to extract total selenium. You can use AAS-Hydride generation or ICP-MS for measurement of Selenium.
Hello Stefano,
I appreciate your inquiry but unfortunately reality is a bit more complicated. The organic selenium species that may be present in consumptive products is specific to the organism. Metabolic mechanisms can yield molecules that include: small anions, zwitterions, polar non-ionic, mid size amino acids, volatile and semi-volatile compounds, non-ionic elemental colloids, to proteins. I have quantitated over 36 different selenium species in specific strains of yeast used in food products. If you want to employ a simplistic method to differentiate between organic and inorganic selenium the most direct method would be to focus on capturing and quantitating the inorganic species then subtracting that from the total selenium concentration (you needs to employ an appropriate digestion fro that feat as well). Cutter and Zhang had some approaches but they did not reflect the complexity of metabolic mechanisms of higher trophic organisms. From a risk assessment perspective this would not be recommended unless you applied the food to the digestive fluids from the organisms consuming the product, perform a simulated digestion, and THEN perform the aforementioned analyses. Even then you would be making gross assumptions regarding the toxicological profile for the residual organic species that have not been documented.
I sincerely hope this helps
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