【作者】 王艳；

【导师】 范世华；

【作者基本信息】 东北大学 ， 分析化学， 2009， 硕士

【摘要】 本文建立了测定·OH的光度分析新方法及顺序注射-光度分析联用技术测定茶叶饮料中的茶多酚的新方法,并获得了令人满意的结果。论文第一部分主要介绍了自由基的形成及特点、自由基的生理效应与危害、羟自由基的测定方法进展,顺序注射分析和光度分析技术。论文第二部分提出了基于在HAc-NaAc缓冲溶液中,利用罗丹明6G(Rh6G)-Co2+-KI-H2O2体系测定·OH的光度分析新方法；探讨了可能的反应机理。采用单因素优化法对试剂的浓度及体积、酸度、反应温度等参数进行了优化。在最佳实验条件下考察了L-抗坏血酸,硫脲,没食子酸等常见抗氧化试剂清除羟自由基的能力,清除能力为：没食子酸>硫脲>L-抗坏血酸,从而验证了本文提出的方法的可靠性；实验比较了Mn2+,Co2+,Fe2+的催化能力。结果表明,三种金属离子中,Co2+的催化能力最强。对几种蔬菜和水果的羟自由基清除能力的测定结果表明,苹果和芹菜的羟自由基清除效率较高,其值分别为78.2%,73.2%。论文第三部分介绍了基于酒石酸亚铁溶液中的亚铁离子能与多酚类物质在磷酸盐缓冲介质(pH=7.50)中生成的蓝紫色络合物在540nm处产生最大吸收的原理,建立了测定茶多酚含量的顺序注射-分光光度分析新方法。茶多酚浓度在5.0-100μg/mL范围内成良好的线性关系,其相关系数为0.9998,方法的精密度为0.68%(n=11),检出限(36)为0.8μg/mL,回收率在92.1%-104%之间,分析频率为36样／小时。该法对实际样品的测定结果与国家标准方法(GB8317-87)结果一致。论文第四部分是对实验的小结。更多还原

【Abstract】 In this dissertation, a new spectrophotometric method for the determination of hydroxyl radical and a sequential injection analysis (SIA) coupled with spectrophotometric method for determining tea polyphenols in tea samples were developed with satisfactory results.The first section of the dissertation concerned the review on the physiological effects and damage of some radicals including hydroxyl radical, the development of analytical methods for the determination of hydroxyl radical, and sequential injection analysis technique was also introduced.For the second section, a novel spectrophotometric method for assessment of hydroxyl radical based on Rhodamine6G (Rh6G)-Co2+-KI-H2O2system in the medium of HAc-NaAc buffer solution was proposed. The possible mechanism of the reaction was discussed, and the experimental parameters including concentration and volume of the reagent and sample, acidity, temperature and other experimental factors were optimized by univariate approach. The antioxidant ability of several antioxidants including L-ascorbic acid, thiourea, and gallic acid were evaluated. The experimental result shows the scavenging activity of antioxidants is gallic acid> thiourea> L-ascorbic acid. The catalytic ability of Co2+is the highest compared with Mn2+and Fe2+. The hydroxyl radical scavenging activity of apple and celery are the highest with scavenging efficiency of78.2%and73.2%, respectively.In the third section, the SIA technique coupled with spectroptometric detection was developed to determine tea polyphenols in tea samples. It is based on a blue-violet complex formed by ferrous tartrate reacted with tea polyphenols in the medium of phosphate buffer solution (pH=7.50), and the reaction product was measured at wavelength540nm. The calibration curve was linear over5.0～100μg/mL with the correlation coefficient of0.9998, a precision (RSD) of0.68%(n=11), a detection limit (3σ) of0.8μg/mL and throughout of36samples/h. Good recoveries were obtained from92.1%to104.0%. The determined results for tea samples by proposed method were in good agreement with that of standard reference method (GB8317-87).In the last section, the characteristics of the two methods were summered.更多还原