电化学快速检测食品中维生素C研究

发布时间：2018-09-11 14:33

【摘要】：维生素C(抗坏血酸,简称Vc),是维持机体正常生命活动所必需的一种生物因子。它能够参与生物体内的许多反应如促进体内胶原合成、神经递质合成、类固醇及有机物质的羟化。适量的Vc,有助于满足人体的需要、增强抵抗疾病的能力及降低癌症发病率。人体缺乏Vc或摄入过量Vc都会对机体造成不良的影响。同时,Vc含量的变化可以作为判断果蔬新鲜程度和耐储藏性的重要指标之一,Vc作为抗氧化剂被广泛用于工业生产中。因此,建立快速有效的Vc检测方法具有重要意义。本研究基于Vc能在电极表面直接发生氧化反应的原理,构建电化学方法用于食品中Vc的快速检测。其主要研究内容如下:1.电极的选择:利用玻碳电极(GCE)、自制铂丝微电极(ME)及自制嵌入式粉末微电极(PME)为工作电极。为提高工作电极的电化学性能,在电极表面引入经混酸液相氧化法处理的纳米材料多壁碳纳米管(MWCNTs),利用不同的分散剂H2O、N,N-二甲基甲酰胺(DMF)分别制备出不同的修饰电极water/MWCNTs/GCE、DMF/MWCNTs/GCE、DMF/carboxyl/MWCNTs/GCE、water/MWCNTs/ME、DMF/MWCNTs/ME、DMF/carboxyl/MWCNTs/ME。通过形貌表征和电化学性能测试优选DMF/carboxyl/MWCNTs/GCE、DMF/carboxyl/MWCNTs/ME为最佳电极。在此研究基础上,将carboxyl/MWCNTs嵌入经腐蚀的ME中,制成carboxyl/MWCNTs/PME。2.检测条件的优化与探究:利用DMF/carboxyl/MWCNTs/GCE、DMF/carboxyl/MWCNTs/ME作为工作电极,对DMF/carboxyl/MWCNTs修饰液浓度进行优化。结果表明,其最优修饰液浓度均为1.0×10-3 g/mL。基于循环伏安法,对pH的影响进行考察,分别得出三种电极DMF/carboxyl/MWCNTs/GCE、DMF/carboxyl/MWCNTs/ME、carboxyl/MWCNTs/PME最优pH环境分别为pH7.0、pH5.0、pH6.0。对Vc在三种电极表面的反应状态进行探究,结果表明Vc在DMF/carboxyl/MWCNTs/GCE、DMF/carboxyl/MWCNTs/ME电极表面均受吸附控制影响,在carboxyl/MWCNTs/PME电极表面受扩散控制影响。3.在以上研究结果的基础上,分别利用DMF/carboxyl/MWCNTs/GCE、DMF/carboxyl/MWCNTs/ME及carboxyl/MWCNTs/PME作为工作电极。其中DMF/carboxyl/MWCNTs/ME、carboxyl/MWCNTs/PME作为工作电极可简化三电极系统为两电极系统,对样品中的Vc含量进行检测研究。结果表明,基于DMF/carboxyl/MWCNTs/GCE电极,Vc的线性响应范围为1.0×10-6~1.0×10-3mol/L,线性方程为Ipa(10-5 A)=0.226c(10-4 mol/L)+1.351,R=0.999,检出限为2.50×10-7 mol/L,回收率为99%~105%;基于DMF/carboxyl/MWCNTs/ME电极,Vc的线性响应范围为1.0×10-4~2.0×10-1 mol/L,线性方程为Ipa(A)=4.197×10-8+1.273×10-5c,R=0.998,检出限为1.0×10-5 mol/L,回收率97%~113%;基于carboxyl/MWCNTs/PME电极,Vc的线性响应范围为5.00×10-6~9.50×10-4 mol/L,线性方程为Ipa(μA)=3.259×10-2+1.801×102c,R=0.997,检出限为4.89×10-7 mol/L,回收率96%~105%。
[Abstract]:Vitamin C (ascorbic acid, abbreviated as Vc),) is a biological factor necessary to maintain normal life activities. It is involved in many reactions in vivo, such as promoting collagen synthesis, neurotransmitter synthesis, steroids and hydroxylation of organic substances. Moderate amount of Vc, helps to meet human needs, increase resistance to disease and reduce the incidence of cancer. Lack of Vc or excessive intake of Vc can cause adverse effects on the body. At the same time, the change of VC content can be used as an important index to judge the freshness and storability of fruits and vegetables. As an antioxidant, VC is widely used in industrial production. Therefore, it is of great significance to establish a fast and effective Vc detection method. Based on the principle that Vc can directly oxidize on the electrode surface, an electrochemical method was constructed for the rapid detection of Vc in food. The main research contents are as follows: 1: 1. Electrode selection: the platinum wire microelectrode (ME) and the self-made embedded powder microelectrode (PME) were used as working electrodes using glassy carbon electrode (GCE),) as the working electrode. In order to improve the electrochemical performance of the working electrode, the multiwalled carbon nanotube (MWCNTs), which was treated by mixed acid solution phase oxidation method, was introduced on the electrode surface to prepare different modified electrode water/MWCNTs/GCE,DMF/MWCNTs/GCE,DMF/carboxyl/MWCNTs/GCE,water/MWCNTs/ME,DMF/MWCNTs/ME,DMF/carboxyl/MWCNTs/ME. by using different dispersant H _ 2O _ N _ (N) N _ (N-dimethylformamide) (DMF). DMF/carboxyl/MWCNTs/GCE,DMF/carboxyl/MWCNTs/ME was selected as the best electrode by morphology characterization and electrochemical performance test. On the basis of this research, carboxyl/MWCNTs is embedded in the corroded ME to make carboxyl/MWCNTs/PME.2.. Optimization of detection conditions: DMF/carboxyl/MWCNTs/GCE,DMF/carboxyl/MWCNTs/ME was used as working electrode to optimize the concentration of DMF/carboxyl/MWCNTs modified solution. The results showed that the optimal concentration of the modified solution was 1.0 脳 10 ~ (-3) g / mL. Based on the cyclic voltammetry, the influence of pH was investigated. The results showed that the optimal pH environment for DMF/carboxyl/MWCNTs/GCE,DMF/carboxyl/MWCNTs/ME,carboxyl/MWCNTs/PME of three electrodes was pH7.0,pH5.0,pH6.0.. The reaction states of Vc on three kinds of electrode surfaces were investigated. The results show that Vc is controlled by adsorption on the surface of DMF/carboxyl/MWCNTs/GCE,DMF/carboxyl/MWCNTs/ME electrode and by diffusion control on the surface of carboxyl/MWCNTs/PME electrode. Based on the above results, DMF/carboxyl/MWCNTs/GCE,DMF/carboxyl/MWCNTs/ME and carboxyl/MWCNTs/PME are used as working electrodes respectively. DMF/carboxyl/MWCNTs/ME,carboxyl/MWCNTs/PME as a working electrode can simplify the three-electrode system to a two-electrode system. The content of Vc in the sample is determined. The results show that 鍩轰簬DMF/carboxyl/MWCNTs/GCE鐢垫瀬,Vc鐨勭嚎鎬у搷搴旇寖鍥翠负1.0脳10-6~1.0脳10-3mol/L,绾挎，

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