The invention relates to the technical field of
nutrient element extraction, and discloses a step-by-step extraction method of organic
selenium in natural
selenium-rich agricultural products, which comprises the following steps: cleaning,
drying and crushing the natural
selenium-rich agricultural products into
fine powder; then sequentially using an
aqueous solution containing a buffer agent, low-concentration
ethanol and a high-concentration
organic solvent for ultrasonic-assisted extraction to respectively obtain water-soluble, hydrophilic, hydrophobic and fat-soluble organic selenium compounds; and finally, combining the extracting solutions in the steps, and carrying out rotary
evaporation concentration and purification treatment to obtain the high-purity organic
selenium compound. Through a step-by-step extraction method, different types of organic selenium compounds in natural selenium-rich agricultural products are efficiently extracted by using the
aqueous solution, the low-concentration
ethanol and the high-concentration
organic solvent respectively under low-temperature and mild conditions, so that high purity and
biological activity are kept, meanwhile, the process flow is simplified, and the production cost is reduced. The
energy consumption and the use of organic solvents are reduced, the environmental
pollution is reduced, and the method is suitable for large-scale industrial production.