Analysis Of Selenium Content And Occurrence Form In Se-rich Tussah Pupa

Selenium(Se)is an essential trace element in human body.Currently the Se-rich functional health foods are vital Se sources for humans.Since Se’s biofunction is highly related to its occurrence,there is difference in the functions,bio-effects,and toxicity between different forms of Se.This work has established a method for analyzing the content and occurrence of Se in the Se-rich tussah pupa,and has provided scientific basis for the technical development of Se-rich tussah pupa heath food.The major results are listed below:1.Establishment of a method for determination of the content of Se in Se-rich tussah pupa,using the Graphite Furnace Atomic Absorption Spectrometry(GFAAS)Employing the tussah pupa as samples,we established a new method for determination of the content of Se in tussah pupa,using theGFAAS.Many factors have been studied,including the condition of temperature programming of microwave-digestion,the type and content of the matrix modifier,the ashing temperature and atomization condition for the determination step using the graphite furnace.The detection limit of this method is 0.26 μg/L,and the precision is 4.3%,and the recovery rate is 93%~103%.The major advantages of this method are low consumption of the reagents,fast and high accuracy.2.Establishment of a method for determination of the content of Se in Se-rich tussah pupa,using the microwave-digestion and Hydride Generation Atomic Fluorescence Spectrometry(HG-AFS)Employing the tussah pupa as samples,we have investigated the method for determination of the content of Se in tussah pupa,using the microwave-digestion and HG-AFS.Simple Variable Method was employed to optimize and select the conditions for determination by the instrumentation,including the high-voltage power,the lamp current,the reducing agent,and the carrier concentration.The detection limit of this method is 0.09 μg/L,and the precision is 1.2%,and the recovery rate is between 94%~103%.Experiments have shown that this method is broad linear range,fast,good sensitive,and with low interference and high accuracy.3.Analysis of the content of inorganic Se and organic Se in Se-rich tussah pupaEmploying the tussah pupa as samples,we employedHG-AFS for the preliminary analysis of inorganic Se and organic Se in Se-rich tussah pupa.After extraction with sonication and 70℃ in water bath,followed by cyclohexane extraction to exclude water-soluble organic Se,we obtained the content of inorganic Se and organic Se in Se-rich tussah pupa.This method has a recovery rate of 92~95% for inorganic Se.The content of organic Se is above 90%.The portion of inorganic Se is related to the nurturing technique of the samples,and is not correlated with the total Se content.4.Preliminary investigation of primary speciation of Se in Se-rich tussah pupaBy employing different solvent extraction methods for the primary speciation,we obtained the primary speciation distribution of alcohol-soluble Se,water-soluble Se,salt-soluble Se,and base-soluble Se,in Se-rich tussah pupa.The Experimentalresults indicate that the content distribution is base-soluble Se> insoluble residue> water-soluble Se>alcohol-soluble Se> salt-soluble Se,in which the base-soluble Se has the largest fraction,between 56% and 71%.Primary speciation analysis shows that the Se in Se-rich tussah pupa occurs as base-soluble Se-proteins.