石墨烯修饰电极在α-生育酚检测中的应用

发布时间：2018-05-07 09:16

本文选题：电催化氧化 + 石墨烯　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：生育酚是维生素E的重要部分。维生素E,是一种常见的脂溶性维生素,包括生育酚和生育三烯酚。常见的有α-,β-,γ-,δ-生育酚,α-,β-,γ-,δ-生育三烯酚这八种形式,由于维生素E结构复杂,异构体种类繁多,在检测上人们一直在寻找更准确便捷的方式。αα-生育酚是维生素E中含量最高活性最强的部分,通常通过检测α-生育酚来测定维生素E。作为人类文明重要的推动者,材料是永恒的瑰宝,在研究者的眼中,辉煌如初。时至今日,常规的材料已然难以满足人们日益增长的需求,常规材料是丰富的无处不在又价格低廉,然而功能的单一决定了它们无法提供多元化的应用。智能和信息应用的发展决定了材料也要逐步向新方向转化,各种先进的材料不断的被发现,材料的多元化亦是一个新的时代。石墨烯是一种仅具有原子厚度的二维材料,它展现了很好的导电性,导热性,柔韧性。在多个领域,都展现出很大的潜力,近年的研究中凸显出各种优异的特性,而其表面官能化的潜力又带来了一个庞大的石墨烯家族,这些石墨烯的衍生物,也被发现了更进一步的优越性。本文的工作主要包括两个部分:1.通过在裸玻碳电极表面电镀掺杂的羧基化石墨烯制备得到石墨烯/玻碳电极用以检测αα-生育酚。相比于现有报道方法的繁复,我们的修饰电极无疑是一支造价低廉且制备简便的电极,检测方式也简单地采用了差分脉冲伏安法(DPV),首先进行富集,之后采用DPV进行检测,得到的响应电流与待测物有线性关系。采用的反应底液是一定比例的乙醇和水混合溶液,因为生育酚是一种脂溶性物质,对于这样的物质在有机相中有更好的溶解性,然而电化学方法对于水相中的反应有更佳的响应,因此选用有机相和水相的混合液可以同时达到增加溶解性和响应信号的目的。2.我们还采用了另一种基底电极电镀碳纳米管。在第二个工作中,基底电极选择为银电极,首先将银电极在氢氧化钠溶液中极化,使其露出表面新鲜的金属银,并且产生纳米氧化银颗粒,之后再电镀石墨烯。这一方面是利用了金属银的催化性,另一方面石墨烯本身也具有催化性,而且电镀至电极表面的石墨烯根据电镜图像也能明显发现增大了电极表面积,这些都有利于响应电流的增加。检测方法采用了我们组在2014年提出的阳极扫描极化反向催化伏安法(PSPRCV),这种方法是采用循环扫描方式,在阳极扫描过程中使电极极化,反向扫描时记录电极上的还原电流。分析物不存在时的电流作为无催化反应的背景电流,然后用分析物存在时记录的电流减去背景电流,得到差值伏安图,即纯净的催化电流-电位曲线。差值电流峰为正负峰形,差值峰电流与分析物浓度具有线性关系,据此进行定量分析。这种方法可以很好的避免背景电流的干扰。
[Abstract]:Tocopherol is an important part of vitamin E. Vitamin E, a common fat-soluble vitamin, includes tocopherol and fertility trienol. There are eight common forms of 伪 -, 尾 -, 纬 -, 未 -tocopherol, 伪 -, 尾 -, 纬 -, 未 -fertility trienol. People have been looking for a more accurate and convenient way of testing. 伪-伪-tocopherol is the most active part of vitamin E. it is usually determined by detecting 伪-tocopherol. As an important promoter of human civilization, material is eternal treasure, in the eyes of researchers, brilliant as ever. Nowadays, it is difficult to meet the increasing demand of conventional materials. Conventional materials are abundant, ubiquitous and cheap. However, because of the single function, they can not provide a variety of applications. The development of intelligence and information applications determines that materials should be gradually transformed to a new direction. All kinds of advanced materials are constantly found, and the diversity of materials is also a new era. Graphene is a two-dimensional material with only atomic thickness. It shows good conductivity, thermal conductivity and flexibility. In many fields, there is great potential. In recent years, various excellent properties have been highlighted, and the potential of surface functionalization has brought about a large family of graphene, derivatives of graphene. Further advantages have also been found. The work of this paper mainly includes two parts: 1. Graphene / glassy carbon electrode was prepared by electroplating carboxylated graphene on the surface of bare glassy carbon electrode to detect 伪 -tocopherol. Compared with the present reported methods, our modified electrode is undoubtedly a cheap and simple electrode. The method of detection is also simple, which is enriched by differential pulse voltammetry, then detected by DPV. The response current obtained is linearly related to the object to be tested. The reaction substrate is a mixture of ethanol and water, because tocopherol is a lipophilic substance that is more soluble in organic phase. However, the electrochemical method has a better response to the reaction in water phase, so the mixture of organic phase and water phase can achieve the purpose of increasing solubility and response signal at the same time. We also used another substrate electrode to electroplate carbon nanotubes. In the second work, the substrate electrode was selected as the silver electrode. Firstly, the silver electrode was polarized in sodium hydroxide solution to expose the fresh metal silver on the surface, and the nano-silver oxide particles were produced, and then graphene was electroplated. On the one hand, it makes use of the catalysis of metallic silver, on the other hand, graphene itself is also catalytic, and the graphene electroplated to the electrode surface can obviously increase the surface area of the electrode according to the electron microscope image. These are beneficial to increase the response current. In this method, the anodic scanning polarization reverse catalytic voltammetry (PSPRCVN) proposed by our group in 2014 is used. This method uses the cyclic scanning method to polarization the electrode during the anodic scanning and records the reduction current on the electrode during reverse scanning. When the analyte does not exist, the current is used as the background current without catalytic reaction, then the background current is subtracted from the current recorded in the presence of the analyte, and the difference voltammogram is obtained, that is, the pure catalytic current-potential curve. The peak of differential current is positive and negative, and the peak current of difference has a linear relationship with the concentration of analyte, according to which the quantitative analysis is carried out. This method can avoid the interference of background current.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ466.5;O657.1

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