蔬菜中常见重金属的测定方法探究及应用

发布时间：2018-02-26 22:36

本文关键词： 蔬菜重金属污染原子吸收　出处：《兰州大学》2017年硕士论文　论文类型：学位论文

【摘要】：蔬菜是人们平常生活里常吃的食物,它能够供给人的身体机能正常运转所必须的营养元素、矿物质和膳食纤维。伴随着人们生活质量的增强,民众越来越愿意采购无污染的健康蔬菜。然而就近几年的调查数据显示,国内诸多都市的周边种植蔬菜的泥土都被某些重元素侵入污染了。甚至有些都市里人们食用的瓜果、菜类和粮食作物中的铅、镉、铬、砷等重金属含量超出国家标准值或与标准值相近。因此,加大对蔬菜生产和流通环节的质量安全控制是当务之急。针对上述现状,本文利用火焰、石墨炉原子吸收分光光度法测定蔬菜中铜、铅、镉、铬元素的含量,用原子荧光光度法测定蔬菜中砷元素的含量。经过实验比较了干法灰化法与传统电热板酸消解、全自动石墨消解仪消解、全自动微波消解仪消解这三种湿法消解法的优劣之处。通过测量生物成分分析标准物质中重金属的含量,对石墨炉原子吸收分光光度法测量蔬菜中铅、镉、铬元素含量的方法,分别进行了检出限、精确度和准确度的比较,并对石墨炉法测定镉时用到的超纯水和硝酸的纯度、基体改进剂硝酸铵和磷酸二氢胺、磷酸二氢铵的浓度以及上机定容体积做对比试验。对原子荧光光度法测定砷,确定出最优的光电倍增管负高压、灯电流、载气流量和硫脲-抗坏血酸的浓度。通过优化实验条件,选择出最佳的实验参数,使得检测结果最为准确,从而确定了最佳检测方案。此后,我们将最佳检测方案应用于实际案例。我们采集青海西宁地区大型超市、农贸市场上常见的10种蔬菜,通过对实验得到的数据进行统计分析,得到了西宁地区常见蔬菜中重金属含量状况和分布规律。这些研究结果,将为今后该地区市场准入时进行蔬菜质量监督提供有效参考并已实际应用于西宁市农产品检测工作当中,为当地农产品安全监测管理做出了一定贡献。
[Abstract]:Vegetables are foods that people eat in their daily lives. They provide the nutrients, minerals and dietary fiber necessary for the normal functioning of the body. People are increasingly willing to buy healthy, pollution-free vegetables. However, surveys in recent years have shown that soil grown around many cities in the country is contaminated by certain heavy elements. Even the fruits and melons eaten by people in some cities. The contents of lead, cadmium, chromium, arsenic and other heavy metals in vegetables and grain crops exceed or are close to the national standard value. Therefore, it is urgent to increase the quality and safety control of vegetable production and circulation. The content of copper, lead, cadmium and chromium in vegetables was determined by flame and graphite furnace atomic absorption spectrophotometry. The content of arsenic in vegetables was determined by atomic fluorescence spectrophotometry. The dry ashing method was compared with the traditional electrothermal plate acid digestion method and the automatic graphite digestion apparatus. The advantages and disadvantages of these three wet digestion methods were analyzed by automatic microwave digestion. The content of lead, cadmium and chromium in vegetables was determined by graphite furnace atomic absorption spectrophotometry by measuring the content of heavy metals in reference materials. The detection limits, accuracy and accuracy were compared respectively. The purity of ultrapure water and nitric acid used in the determination of cadmium by graphite furnace method, the matrix modifiers ammonium nitrate and diamine phosphate were compared. The concentration and volumetric volume of ammonium dihydrogen phosphate were compared. The optimum photomultiplier tube negative high voltage and lamp current were determined by atomic fluorescence spectrophotometry. Carrier gas flow rate and thiourea-ascorbic acid concentration. By optimizing the experimental conditions, the best experimental parameters are selected, so that the detection results are the most accurate, thus the best detection scheme is determined. We apply the best test scheme to practical cases. We collect 10 kinds of vegetables that are common in large supermarkets and farmers' markets in Xining area, Qinghai, and make statistical analysis on the data obtained from the experiments. The contents and distribution of heavy metals in common vegetables in Xining area were obtained. It will provide an effective reference for the vegetable quality supervision in the future market access and has been applied to the detection of agricultural products in Xining City. It has made a certain contribution to the safety monitoring and management of local agricultural products.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.31;TS255.7

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