Research Of Selenium Enrichment Characteristic And Speciation Distribution In Carrot

As an important trace element for human health, selenium can influence some body functions of organisms, and then affect the health of people. Mainly through the intaking of foods, human body is able to absorb selenium. It has an important theoretical and practical significance to research the safe way of making selenium enter food chain. There is a safe and effective approach to obtain the production of rich-selenium, that turning the inorganic selenium into organic selenium by the plants uptake. Carrots, as a kind of high nutrition of crops, had been reported by many domestic and foreign relevant reports about that this kind of crop contains a lot of beneficial to human body composition. And the doctor of traditional Chinese medicine thought that carrots had drug action. We have studied selenium enrichment characteristic of carrots and the chemical forms of selenium. We draw the following conclusions:(1) Applying exogenous selenium to soil could influence the characteristic of carrots, such as growth, chlorophyll, photosynthetic indicators and so on. Low concentration of selenium could not lead to the increased production. But when the concentration of selenium was over 160 mg·kg-1, the production was increased. Because the maximum value of gradient of applying selenium was 200 mg-kg"1 whether a higher concentration of selenium could influence the yield of carrots or not needed further study.(2) Determination of selenium is the ground and underground parts of carrots by Hydride Genernation (HG)-AFS with Microwave. The effects of digestive reagent and digestion conditions on sample preparation were discussed; 5 ml HNO3 and 2 ml H2O2 was determined as the conditions of oxidizing agent; optimizing operation conditions:(1) 2 min、0.2 Mpa; (2) 3 min、0.5 Mpa; (3) 3 min、0.7 Mpa; (4) 5 min、 1.0 Mpa.The carrots had enrichment effect for exogenous selenium, and enrichment ability of overground parts of carrots is better than that of underground parts of carrots. Low concentration of selenium could enhanced the absorption of carrots for selenium, but when the concentration of selenium was over 160 mg·kg-1, the absorption of carrots for selenium was restrained.(3) Using water, ethanol, weak base (0.1moL·L-1, NaOH), weak acid (0.1moL·L-1, HCL) and Tris-HCL (pH= 7.2), reagent extraction agent on the different forms of selenium in plant samples were extracted. The results showed that the order of selenium content in four type of extraction was:H2O> NaOH>Tris-HCL> HCL. The mainly existence of selenium were water-soluble (26.12% of total selenium) and Alkali soluble state (25.33% of total selenium).(4)The study preliminarily discussed the effects of foliar application of selenium and soil se-supplement on carrots’selenium-rich ability and physiological property. And the result showed that foliar selenium has little effect on chlorophyll content, but the variation coefficient of chlorophyll was higher than method of soil se-supplement. Compared with method of soil se-supplement, the effect of foliar application of selenium on selenium enrichment was not obvious, and selenium content of foliar application of selenium was lower than the selenium content of soil se-supplement, which had same applying selenium gradient to foliar application of selenium. However, foliar application of selenium promoted the growth of carrots.(5) HPLC-LC-MS method to quantify three kinds of dissociative selenoaminoacid. Ultrasonic-assisted water extraction was confirmed as the best condition of free amino acid extraction. The majorization of mass spectrometer conditions (Fragmentor, impact energy) for carrots’selenium enrichment determination by HPLC-LC-MS was made. MRM method was also used in this study. When the concentration of selenium enrichment was 80 mg·kg-1, the contents of three kinds of dissociative selenoaminoacid reached the maximums, respectively:SeMet 225.74 μg·kg-1, SeMC 698.57μg·kg-1,SeCys 146.99 μg·kg-1. The amount of selenium in the three selenoaminoacid comprised 40% of total selenium. Therefore, consumption of se-enriched carrots could be a safe and effective way of selenium supplementation for human body.