共查询到18条相似文献,搜索用时 62 毫秒
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单粒子气溶胶的基质辅助激光解吸/电离飞行时间质谱技术具有快速在线检测环境大气生物气溶胶的潜力.以a-环糊精为分析物,实验研究了吡啶羧酸、2,5-二羟基苯甲酸、芥子酸、阿魏酸四种常用基质材料的效果,考察基质与分析物的摩尔比对分析物单粒子激光质谱信号的影响.实验结果表明阿魏酸做基质时质谱命中率及分析物质谱信号峰检测效率最高,吡啶羧酸做基质时的分析物质谱信号峰激发率最高,信号峰强度最强.吡啶羧酸对分析物摩尔比为100:1时,分析物质谱信号检测效率最高. 相似文献
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单粒子气溶胶的基质辅助激光解吸/电离飞行时间质谱技术具有快速在线检测环境大气生物气溶胶的潜力.以α-环糊精为分析物,实验研究了吡啶羧酸、2,5-二羟基苯甲酸、芥子酸、阿魏酸四种常用基质材料的效果,考察基质与分析物的摩尔比对分析物单粒子激光质谱信号的影响.实验结果表明阿魏酸做基质时质谱命中率及分析物质谱信号峰检测效率最高,吡啶羧酸做基质时的分析物质谱信号峰激发率最高,信号峰强度最强.吡啶羧酸对分析物摩尔比为100:1时,分析物质谱信号检测效率最高. 相似文献
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基于模糊聚类算法的大气粒子激光电离质谱数据分析 总被引:1,自引:0,他引:1
实验室自行研制了一台大气气溶胶飞行时间激光质谱仪(ATOFLMS),它可以在线地对气溶胶单粒子进行物理和化学特性分析,利用双束连续激光对单个粒子的空气动力学粒径进行测量,并通过飞行时间完成单粒子化学成分的检测。该仪器在运行过程中将产生海量的实验数据,对这些数据的快速、自动处理并提取有价值的信息是整机系统的关键之一。文章介绍模糊聚类算法FCM(fuzzy c-means)在大气气溶胶单粒子聚类分析中的成功运用。利用该算法对连续24 h采集的室内空气气溶胶单粒子质谱数据进行了聚类分析,在得到的5个聚类结果中包含了无机的海盐粒子、矿物质粒子以及其他的三种二次气溶胶成分粒子类型。在对室内空气气溶胶粒子的粒径进行实时检测的结果表明室内可吸入颗粒物以细粒子为主,其中大于1 μm的粒子所占比重较小。小于1 μm的粒子均占95%以上, 在0.4~0.8 μm之间的粒子占据主要部分。 相似文献
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用激光解吸附电离飞行时间质谱法检测悬浮土壤颗粒物 总被引:1,自引:0,他引:1
在自行研制的气溶胶飞行时间激光质谱仪(ATOFLMS)上实时探测单个悬浮土壤颗粒的粒径和化学成分。利用双束连续激光对单个粒子的空气动力学粒径进行测量,并用266 nm的Nd∶YAG激光器对气溶胶单粒子进行解吸附电离作用,产物离子通过飞行时间质谱仪的无场漂移区后完成单粒子化学成分的检测。本实验中使用了4个不同地区的土壤样本,在实验室内对分析的样本进行预处理和再悬浮,通过导管引入ATOFLMS进行测量,得到大量单粒子的粒径和质谱数据。发现在众多的单粒子的阳离子质谱中,金属成分以地壳元素(Fe, K, Al, Ca)为主,在其他阳离子质谱中包含了Mg和Na等。对悬浮土壤粒子的粒径进行实时检测的结果表明这些粒子多以粗粒子为主, 粒径主要集中在1~2 μm。实验结果表明该仪器在大气气溶胶环境监测及相关研究领域具有重要的实用价值。 相似文献
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基于自适应共振神经网络的单粒子激光电离质谱数据分析 总被引:1,自引:0,他引:1
气溶胶激光飞行时间质谱仪(ALUOFMS)可以在线地对气溶胶单粒子进行物理和化学特性分析,利用双束连续激光对单个粒子的空气动力学粒径进行测量,并通过飞行时间完成单粒子化学成分的检测。该仪器在运行过程中将产生海量的实验数据,对这些数据快速、自动处理并提取有价值的信息是整机系统的关键之一。文章介绍了基于神经网络的自适应共振算法(ART-2a)在随机混和的氯化钠、氯化钙、邻苯二甲酸二正辛酯(DOP)和2,5二羟基苯甲酸(DHB)气溶胶单粒子聚类分析中的成功运用。同以往的质谱分析方法相比,ART-2a可以实现对任意多和任意复杂的输入模式进行自组织,自适应和自稳定的快速识别,更有利于质谱数据的分析。实验结果表明,当警戒值为0.40,学习速率为0.05以及迭代次数为6时,ART-2a可以成功地对这四种物质进行分类,同时得到4类物质的聚类中心,每类的聚类中心都能很好的代表该类物质的特征。 相似文献
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基于微分法精确测量气溶胶飞行时间的新方法 总被引:4,自引:1,他引:3
利用飞行时间气溶胶粒子束光谱技术对大气气溶胶牲子粒谱分布进行监测是精确测量大气气溶胶粒子粒径大小及浓度的典型方法.而精确测量气溶胶粒子飞行时间是实现粒径谱精确监测的关键.利用微分法对门限电平比较法进行优化改进,利用信号微分后的零点对应信号最大值的特点,将飞行时间提取中变化的门限电平的比较转换成零电平的比较,设计了一种精确测量气溶胶粒子飞行时间的方法.该方法不但可以忽略因气溶胶粒子大小而引起的散射光强弱变化,而且,即使散射光双峰信号并非理想的对称信号,该方法也能精确地测得飞行时间. 相似文献
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Yutaka Aoki Atsuhiko Toyama Takashi Shimada Tetsuyoshi Sugita Chikage Aoki Yukari Umino Atsushi Suzuki Daisuke Aoki Yataro Daigo Yusuke Nakamura Taka-Aki Sato 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2007,83(7):205-214
Significant advances have been made in the past decade in the field of mass spectrometry imaging (MS imaging). It is a relatively unestablished technique aimed at direct, high-sensitive and spatially exclusive detection of biological molecules from the surface of tissue sections, so that semi-quantitative distribution map of the analyte can be reconstituted from the mass spectra obtained. There is tremendous potential in its application especially in clinical field, such as biomarker discovery or pharmacokinetic study. However, vast majority of the work has been performed on frozen tissue sections, while it remains generally unpractical to produce frozen sections with clinically resected tumor samples. Here we report our novel sample preparation technique that enabled MS imaging from formalin-fixed paraffin embedded (FFPE) tissue section, including retrospective archive as old as 11 years. FFPE sections were first dewaxed with pre-warmed xylene, and exposed tissue surface was enzymatically digested in nanoliter scale droplets to retain analyte localization. As a result, we succeeded in obtaining MS images of peptide peaks derived from several proteins, identified by MS/MS analysis, using ovarian cancer FFPE sections. The qualities of mass spectra obtained by this method were not significantly different from those obtained from frozen sections. By this, we opened the door to retrospective study of past clinical cases in aim to discover molecular biomarker. 相似文献
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Xe-Kr laser induced collisional ionization system and experimental preparation of its initial state: Four-photon resonant excitation 下载免费PDF全文
This paper proposes a novel one-colour Xe-Kr laser induced collisional ionization system. Considering the level scheme of the system, it finds that the initial state of the reaction--the four 4f levels with even J of Xe-can be prepared through method of four-photon resonant excitation by dye laser with wavelength of -440 nm. Absorption of an additional photon (the transfer laser) of the same wavelength will complete the laser induced collisional ionization process. The resonance enhanced ionization spectrum of Xe by four laser photons at -440nm is measured through time-of-flight mass spectrometry, this aims at the preparation of the initial state of the system proposed. The Stark broadening of the measured spectrum is observed and consistent with the previous study. Analysis of the measured resonance ionization spectrum implies the feasibility of -440 nm four-photon resonant excitation of the initial 4f state of the Xe Kr system proposed in this paper, which prepares for a further experiment of laser induced collisional ionization. 相似文献
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Mohammadreza Shariatgorji Nahid Amini Leopold L. Ilag 《Journal of nanoparticle research》2009,11(6):1509-1512
Conventional matrix-assisted laser desorption/ionization mass spectrometry is limited to analyses of higher molecular weight
compounds due to high background noise generated by the matrix in the lower mass region. Surface-assisted laser desorption/ionization
(SALDI) mass spectrometry is an alternative solution to this problem. Nanoparticles, structured silicon surfaces and carbon
allotropes are commonly used as SALDI surfaces. Here, for the first time, we demonstrate the application of silicon nitride
nanoparticles as a suitable medium for laser desorption/ionization of small drug molecules. 相似文献
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利用脉宽为5 ns脉冲Nd: YAG 355 nm激光在功率密度为1011–1012 W/cm2条件下实现了甲醛含水团簇多光子电离, 并用飞行时间质谱对其电离产物和电离过程进行了研究. 实验中观测到了甲醛的质子化团簇系列 (CH2O)nH+(n=1–4), 甲醛的去质子化团簇系列(CH2O)nCHO+ (n=1–3), 以及两个起源于H2CO去质子和质子化的含水团簇系列HCO+(H2O)n(n=1,3,5)和H3CO+(H2O)n(n=1,3,5), 并对其中的一些团簇结构构型进行了猜测. 研究在不同的激光功率密度下甲醛团簇质谱峰的变换情况, 当激光密度达到9.3× 1011 W/cm2, 开始出现CH2O和H2O本体及其光致碎片的信号, 但对应的各质量峰没有明显地分辨开, 而是以包络的形式出现, 这是激光电离产生高能离子释放的一种表现, 提出认等离子体动力学鞘层加速机制(模型)来解释高能离子形成的物理机制.
关键词:
甲醛
团簇
飞行时间质谱
激光电离 相似文献
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We report studies on the multiple ionization of the N2 molecule using intense, femtosecond laser pulses. We present details of the experimental characterisation of the light pulses
and analysis and detection of the ions produced. Precautions to be taken in intense field ionization experiments are discussed.
We illustrate the retrieval of information about different aspects of the ionization process (such as, kinetic energies of
the fragments produced, dissociation bond lengths and information on the precursors to fragmentation) using coincidence techniques.
We report results of the first measurements of the angular distribution of a highly charged fragment, N3+. 相似文献