【作者】 李娜；

【导师】 王富华；

【作者基本信息】 华中农业大学 ， 植物营养， 2011， 硕士

【摘要】 硒是人体必需的微量营养元素之一,虽然其在环境和植物体中的含量很小,但它对人体有着巨大的生物功效。由于硒的生物有效性和致毒性都与其形态密切相关,现在常用总硒含量来评价其营养性和毒性存在较大不足,因此建立硒的分析方法并推广应用十分必要。本研究就是要以生物中最常见的四种硒形态为基础,建立用HPLC-HG-AFS联用测定植物性食品中硒形态的方法。本项研究的主要特点和成果有：1.研究对象具有很强的代表性。根据硒本身的营养性、毒性特点以及植物对硒的吸收特点等因素,将植物性食品按植物的科属分类,选择十字花科、百合科、豆科等植物性食品进行分析,并在条件允许的情况下对尽可能多的样品进行分析测定。2.确立了比较适宜的硒形态分析提取方法。通过对比测试分析,在沸水浴提取、高氯酸乙醇提取、甲醇水提取、酶提取四种前处理方法中,以甲醇水提取的提取效率较高。3.在本实验条件下,建立了仪器分析的最佳条件。对仪器分析中每一个参数进行了样品检测研究,提出仪器的最佳试验参数为：HPLC部分(流动相为60 mmol/L的(NH4)2HP04,其pH为5.5),HG部分(还原剂为1.5%(m/v)的KBH4+0.5%KOH (m/v)+0.1%KI,载流为15%的盐酸),AFS部分(硒空心阴极灯灯电流为45 mA,光电倍增管负高压为300 V,载气流速为400 mL/min,屏蔽气流速为900 mL/min)。4.经可靠性分析认为提出的检测方法准确可靠。对所建立的方法进行了方法检出限、回收率、精密度等试验,四种形态硒的检出限分别为SeCys6.29-6.46μg/L, Se(Ⅳ)5.46-5.57μg/L, SeMet17.15-17.99μg/L, Se(Ⅵ)7.56-7.90μg/L;用某一浓度的混标连续进样7次,四种形态硒的保留时间和峰面积的相对标准偏差分别为：SeCys 0.6%、2.6%, Se(Ⅳ) 0.1%、2.6%, SeMet0.8%、2.5%, Se(Ⅵ)0.2%、4.7%;四种形态硒的峰面积和其浓度呈现良好的线性关系,相关系数均大于0.999。5.开展了新方法的应用研究。将建立的方法对尽可能多的植物性食品中硒进行测试,结果表明,不同样品中不同形态硒的分离效果良好,部分号称富硒的食品名不符实,其硒含量是很低的。更多还原

【Abstract】 Selenium is one of the necessary microelements to human beings, with its tiny content in the environment and plant. It has significant biological implications to us. It is not fit to judge the nutrition and toxicity of selenium by the content of total selenium, owing to the significant relevance between its availability and speciations. So it is necessary to establish and extend the method for speciation analysis of selenium. Choosing four speciations of selenium with significant biological meanings, this paper has given a method for the determinations of speciations of selenium in vegetal food with HPLC-HG-AFS techniques. The results are as follows:1. The objects of this study has great representativeness. We clsssify the vegetal food according to the nutrition, toxicity, absorbtion of selenium and choose the samples of cruciferae、liliaceae、leguminosae etc to do the analysis. We have done this as many as we could.2. Establish a better extraction method. Among the four extractions including boiling water extraction, perchloric acid-ethanol extraction, methanol-water extraction, enzyme extraction, methanol-water extraction is better.3. Establish the better parameters of the instrument. Of the HPLC part, the mobile phase should be (NH4)2HPO4,60 mmol/L, with its pH being 5.5; Of the HG part, reducing ageats should be 1.5%KBH4(m/v)+0.5%KOH (m/v)+0.1%KI (m/v) and the carrier solution. 15%HCl(v/v); Of the AFS part, selenium hollow cathode lamp current should be 45 mA: the negative high voltage of photomultiplier tube should be 300V; the flow rate of carrier gas should be 400 mL/min, and the flow rate of make up gas,600 mL/min.4. Assessments of the method:Detections of SeCys, Se(Ⅳ) SeMet, Se(Ⅵ) are respectively 6.29-6.46μg/L,5.46-5.57μg/L,17.15-17.99μg/L,7.56-7.90μg/L; Seven determinations of the same standard solution containing four speciations of selenium showed that the RSDs of the retention times and peak areas are as follows:SeCys 0.6%, 2.6%; Se(Ⅳ) 0.1%,2.6%; SeMet0.8%,2.5%; Se(Ⅵ) 0.2%,4.7%; The linear correlation coefficients of the four speciations between the peak areas and concentrations are satisfactory, all above 0.999. 5. Applications of the method. The method was applied to vegetal food as many as possible and the results showed that the content of selenium is rather low in most samples, with no speciation of selenium being detected. Only in peanut and soybean were tiny speciations of selenium detected. Meanwhile, it is found that the contents of selenium in some "selenium-riched" food do not match their labels. In other word, the real value of selenium content maybe very low.更多还原