中药是具有中华民族传统文化特色的古老产业，也是世界医药学的重要 组成部分。但是在中药的生长形成与加工炮制中极易引入重金属污染，从而 影响中药品质甚至危害患者健康。快速对中药内重金属进行检测是十分有必 要的。激光诱导击穿光谱技术（Laser-Induced Breakdown Spectroscopy， LIBS）十分适用于金属检测，具有一次能检测多种元素，基本无需样品预处 理，操作简便等优点。本文对激光诱导击穿光谱技术应用于中药重金属检测 的可行性进行了探究。 本文充分调研了国内外研究现状及实验仪器的性能，初步分析了 LIBS 技术应用于中药重金属检验的可行性。采用 Nd:YAG 纳秒激光器构建基于连续 激发方式的 LIBS 检测系统，对黄连、附片和茯苓中的 Cu、Pb 两种元素进行 检测，确定了该系统的最佳试验条件和参数，并进行了定性定量分析。为提 高 LIBS 检测系统的检测限，依据中药样品的物理特性，改进激光激发方式， 进一步优化 LIBS 检测系统。经过实验对比表明，优化后的 LIBS 检测系统能 获得更高的信噪比和检测限；采用 LIBS 技术对中药重金属污染进行直接检测 是可行且有效的。 关键词，激光诱导击穿光谱 中药 重金属 可行性研究西南科技大学硕士研究生学位报告 第Ⅱ页 Abstract Traditional Chinese medicine is the traditional culture of the China, it’s also part of the world medicine. However, the growth and processing of traditional Chinese medicine is easy to introduce heavy metal pollution, which affects the quality of Chinese medicine and even endanger the health of patients. So it is necessary to detect the heavy metal in Chinese traditional medicine. Laser induced breakdown spectroscopy is suitable for metal detection, which has many advantages like detect many kinds of elements at once, no need of sample pretreatment, simple operation and so on. In this paper, the feasibility of laser induced breakdown spectroscopy applied to the detection of heavy metals in traditional Chinese medicine was studied. In this paper, the present research situation of the domestic and foreign and the performance of the experimental instrument are fully investigated. The feasibility of applying LIBS technology to the heavy metal inspection of Chinese medicine was analyzed. Nd: YAG nanosecond laser is constructed based on continuous excitation of the LIBS detection system, the Cu, Pb in Coptis chinensis, Aconite root and Poria cocos were detected. The optimum test conditions and parameters of the system were determined, and the qualitative and quantitative analysis were carried out. In order to improve the detection limit of LIBS detection system, based on the physical characteristics of Chinese medicine samples, improve the laser excitation mode, and further optimize the LIBS detection system. The experimental results show that the optimized LIBS detection system can obtain a higher signal to noise ratio and detection limit. It is feasible and effective to directly detect the heavy metal pollution of traditional Chinese medicine by using LIBS technology. Key words: Laser-Induced Breakdown Spectroscopy; traditional Chinese medicine; heavy metal; feasibility study西南科技大学硕士研究生学位报告 第Ⅲ页 目 录 1 绪论............................................................................................................................1 1.1 研究背景及意义.........................................................................................1 1.1.1 中药重金属污染现状...................................................................1 1.1.2 中药重金属污染途径与危害......................................................2 1.1.3 中药重金属控制指标...................................................................2 1.2 现有重金属检测方法................................................................................4 1.2.1 高效液相色谱法............................................................................4 1.2.2 原子吸收光谱法............................................................................4 1.2.3 原子荧光光谱法............................................................................4 1.2.4 电感耦合等离子体质谱法..........................................................5 1.2.5 激光诱导击穿光谱技术...............................................................5 1.3 国内外研究现状.........................................................................................5 1.3.1 国内研究现状.................................................................................5 1.3.2 国外研究现状.................................................................................7 1.4 本文主要研究内容....................................................................................8 2 LIBS 理论基础及用于中药检测的可行性分析..............................................9 2.1 激光诱导击穿光谱基本理论..................................................................9 2.2 激光诱导等离子体基本特性................................................................10 2.2.1 等离子体局部热平衡.................................................................10 2.2.2 等离子体温度...............................................................................11 2.2.3 等离子体电子密度......................................................................11 2.3 激光诱导击穿光谱基本特性................................................................12 2.3.1 等离子体辐射过程..................................................................... 12 2.3.2 特征谱线形成过程..................................................................... 13 2.4 激光诱导击穿光谱技术特点及应用..................................................13 2.5 激光诱导击穿光谱技术影响因素.......................................................14 2.5.1 激光能量........................................................................................14 2.5.2 延迟时间........................................................................................14西南科技大学硕士研究生学位报告 第Ⅳ页 2.5.3 环境气压........................................................................................14 2.5.4 光纤探测角度...............................................................................14 2.6 激光诱导击穿光谱技术定量分析方法..............................................15 2.6.1 传统强度定标法..........................................................................15 2.6.2 内标法............................................................................................16 2.6.3 自由定标法...................................................................................16 2.7 LIBS 用于中药内重金属检测的可行性分析....................................17 2.8 本章小结....................................................................................................18 3 LIBS 中药重金属连续激发系统设计分析与搭建....................................... 19 3.1 激光诱导击穿光谱系统设计分析.......................................................19 3.1.1 中药对象的确定..........................................................................19 3.1.2 待测元素及分析谱线的确定...................................................19 3.2 激光诱导击穿光谱系统设计搭建.......................................................21 3.3 系统组成部件...........................................................................................22 3.3.1 激光器............................................................................................22 3.3.2 光谱仪............................................................................................24 3.3.3 延迟触发器...................................................................................25 3.3.4 三维移动平台...............................................................................26 3.3.5 激光能量传感器..........................................................................27 3.3.6 激光能量计表头..........................................................................27 3.4 本章小结....................................................................................................28 4 中药内重金属 LIBS 检测关键参数优化研究..............................................29 4.1 真实含量检测...........................................................................................29 4.2 实验样品制备...........................................................................................29 4.2.1 含 Cu 样品.....................................................................................30 4.2.2 含 Pb 样品.....................................................................................30 4.3 激光能量特性分析..................................................................................30 4.3.1 Cu 元素激光能量特性分析.......................................................30 4.3.2 Pb 元素激光能量特性分析........................................................34 4.4 延迟时间特性分析..................................................................................38 4.4.1 Cu 元素延迟时间特性分析.......................................................38西南科技大学硕士研究生学位报告 第Ⅴ页 4.4.2 Pb 元素延迟时间特性分析........................................................42 4.5 本章小结....................................................................................................45 5 LIBS 的中药重金属检测结果分析及方法改进............................................46 5.1 定量分析中内标元素的选取................................................................46 5.1.1 原子吸收光谱法对 Ca 含量的检测........................................46 5.1.2 Cu 的内标参量选取.....................................................................46 5.1.3 Pb 元素内标参量选取.................................................................47 5.2 定量分析....................................................................................................48 5.2.1 Cu 的定量分析..............................................................................48 5.2.2 Pb 的定量分析..............................................................................51 5.2.3 内标法对线性拟合度的影响分析..........................................53 5.2.4 检测限与国家标准的对比及分析..........................................54 5.2.5 改进方向分析...............................................................................54 5.3 中药内重金属激光诱导击穿光谱检测方法优化设计...................55 5.3.1 示波器............................................................................................57 5.3.2 光电探测器...................................................................................59 5.3.3 电子定时器...................................................................................59 5.3.4 高精度快门...................................................................................60 5.4 方法优化前后的结果对比....................................................................61 5.4.1 信号抖动........................................................................................61 5.4.2 信噪比............................................................................................65 5.4.3 线性拟合度...................................................................................70 5.4.4 检测限............................................................................................71 5.4.5 小结.................................................................................................71 5.5 展望.............................................................................................................72 5.5.1 样品状态........................................................................................72 5.5.2 激光脉冲........................................................................................72 5.5.3 缓冲气体........................................................................................73 5.5.4 实验器件........................................................................................73 5.6 本章小结....................................................................................................74 总结与展望.................................................................................................................75西南科技大学硕士研究生学位报告 第Ⅵ页 致谢.....................................................................................................................77