1、 气流式微富集论文：气流式微富集系统研究与设计【中文摘要】顶空液相微萃取(HS-LPME)技术是一种集分离、纯化、浓缩为一体的样品前处理方法,该技术已经广泛应用于对多种不同样品中挥发性或半挥发性目标物的富集。在该技术中,提高样品基质的温度并降低萃取溶剂的温度是提高富集效率的关键,为了使样品基质获取高温,萃取溶剂获取低温,许多学者提出了各种各样的加热和制冷方法,但这些方法广泛存在着以下几个缺点：装置体积大、操作不便、温度难以控制、难以实现在线富集等等。此外,HS-LPME 技术是在封闭系统中进行富集实验的,在给定的温度和压强下,顶空气相中所含目标化合物的量是固定的,对低蒸汽压目标物的富集效率不佳
2、。为了能够实现对各种不同样品中包含低蒸汽压目标物在内的挥发性和半挥发性痕量目标物快速、自动、高效的富集,本学位论文研究和开发了基于气体吹扫微量注射器萃取技术(GP-MSE)的气流式微富集系统。在该系统中,设计了半导体冷凝器和微型加热器,分别用于对萃取溶剂制冷和对样品加热。对制冷和加热温度的控制是以AT89C52单片机为控制核心,通过比较由温度采集电路采集到的实时温度值与设定温度值的差值,利用改进的 PID控制算法输出 PWM控制信号驱动执行元件制冷片及加热片,使系统达到预设温度。此外,惰性气体通过不锈钢进气管被持续引入系统,使系统成为开放的系统,通过单片机控制质量流量控制器(MFC)对气体流量
3、进行检测与调节,使系统中通入的惰性气体流量达到设定值。系统采用 LCM141液晶显示模块实时显示当前制冷及加热温度、气体流量值及定时时间。利用本学位论文所研究设计的气流式微富集系统及传统的 HS-LPME技术分别对加入 18种多环芳烃的加料样品进行富集实验,验证了气流式微富集系统具有更好的富集特性。然后,利用该系统对加料的长白山植物和土壤样品进行萃取实验,GC-MS 分析结果表明,使用气流式微富集系统能获得很好的富集效率并且重现性好,而对长白山植物和土壤的实际样品,采用气流式微富集系统富集的效果与使用 Soxhlet萃取法类似。实验结果表明,气流式微富集系统在对各种样品中挥发性和半挥发性的化学
4、物的分析应用中具有很大的潜力。【英文摘要】Headspace liquid phase microextraction (HS-LPME), which integrates extraction, cleanup and concentration, is a sample pretreatment technique that widely used in the enrichment of volatile and semivolatile target compounds from many different kinds of samples. In this technique,
5、improving the temperature of sample matrixes and reducing the temperature of extraction solvent are key points to improve enrichment efficiency. In order to obtain a high temperature of sample matrix and a low temperature of extraction solvent, many scholars have proposed various kinds of heating an
6、d refrigerating methods. These methods have some shortcomings such as bigness of the device, inconvenience of the operation, difficult control of the temperature and difficult achievement of online enrichment. In addition, enrichment experiments are performed in closed system in HS-LPME technique. U
7、nder a given temperature and pressure, the amount of target compounds entering the headspace in HS-LPME is constant with the result that the enrichment factor for the low vapor pressure target compound is not good.To achieve rapid, automatic and efficient extraction of volatile and semivolatile trac
8、e target compounds which include low vapor pressure target compound from different kinds of samples, an airflow microenrichment system based on gas purge microsyringe extraction was researched and developed in this dissertation. In this system, semiconductor condenser and microheater were designed r
9、espectively to cool the extraction solvent and to heat the sample. The control of refrigerating and heating temperatures were achieved by AT89C52 microcontroller, which compared the temperature value that collected by temperature collecting circuit with the set one and then used improved PID control
10、 algorithm to export PWM control signal for driving the execution components-refrigeration piece and heater band, making the inert gas introduced into the system reach the set value. The system adopted LCM141 LCD module to display the current refrigerating and heating temperatures, gas flow rate and
11、 timing time.The airflow microenrichment system researched and designed in this dissertation has been proved to be of better enrichment characteristics after usages of it and original HS-LPME technique respectively for the enrichement of 18 PAHs in spiked sample. Then, enrichment experiments for the
12、 spiked Changbai Mountain plant and soil samples were performed using this system. GC-MS analysis results indicated that high enrichment efficiency was obtained from airflow microenrichment system and the system revealed good reproducibility. For the real plant and soil samples from Changbai Mountai
13、n, the results of this system were similar to the results obtained from Soxhlet extraction technique. The experimental results demonstrate that airflow microenrichment system is potential in analysis of volatile and semivolatile chemicals from various kinds of samples.【关键词】气流式微富集 冷凝器 加热器 单片机 流量控制器【英
14、文关键词】airflow microenrichment condenser heater microcontroller flow controller【目录】气流式微富集系统研究与设计 摘要 7-8 Abstract 8-9 第 1章 绪论 14-19 1.1 研究目的及意义 14-15 1.2 国内外相关领域的研究现状 15-17 1.3 研究内容与主要工作 17 1.4 本文结构 17-19 第 2章 气流式微富集相关理论与技术 19-26 2.1 引言 19 2.2 微富集技术 19-20 2.3 半导体制冷原理 20-22 2.4 质量流量检测原理 22-23 2.5 PID控制算
15、法 23-25 2.5.1 经典 PID控制算法 23-24 2.5.2改进的 PID控制算法 24-25 2.6 本章小结 25-26 第 3章 气流式微富集系统的硬件和软件设计 26-46 3.1系统结构组成 26-27 3.2 半导体冷凝器设计 27-30 3.2.1 半导体制冷器结构 27-28 3.2.2 半导体冷凝器控制电路 28-29 3.2.3 制冷温度检测电路 29-30 3.2.4 半导体制冷片驱动电路 30 3.3 微型加热器设计 30-36 3.3.1 微型加热器结构 30-32 3.3.2 微型加热器控制电路 32 3.3.3 加热温度检测与放大电路 32-33 3.
16、3.4 AT89C52与 ADS1286的接口电路 33-35 3.3.5 加热片驱动电路 35-36 3.4 气体流量检测与调节电路 36-37 3.5 其他外围电路 37-42 3.5.1 报警电路 37-38 3.5.2 电源电路 38-39 3.5.3 AT89C52与液晶显示模块的接口电路 39-40 3.5.4 AT89C52与键盘的接口电路 40-41 3.5.5 AT89C52与 AT24C02存储器的接口电路 41-42 3.6 系统软件设计 42-45 3.6.1 系统主程序 42-43 3.6.2 PID控制子程序 43 3.6.3 温度检测与控制子程序 43-44 3.6.4 气体流量检测与控制子程序 44-45 3.7 本章小结 45-46 第 4章 实验结果及分析 46-53 4.1 引言 46 4.2 参数对富集效率的影响 46-49 4.2.1 气体流量对富集效率的影响 46-47 4.2.2 温度对富集效率的影响 47-49 4.3 对比实验及结果分析 49-51 4.4 本章小结 51-53 结论 53-54 参考文献 54-57 附录 系统电路图 57-58 攻读硕士学位期间发表的论文 58-59 致谢 59
