Name: real-time breath analysis by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry
Uploaded: 2018-03-09T12:30:00.000+00:00
Duration: 8 min 23 s
Description: Watch this Scientific Journal Video about Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry at JoVE.com

这项工作得到了中国国家自然科学基金 (91543117 号) 的资助。

警告: 使用前请查阅所有相关的材料安全数据表 (MSDS)。请使用适当的个人防护设备,例如, 实验室外套, 手套, 护目镜, 全长长裤和闭合脚趾鞋)。
1. 设置 Sec-nanoESI 源
<ol><li>根据局过程设置 Sec nanoESI 源,即, 引入呼吸气体, 使其与电喷雾羽流相交, 并被带电的水滴电离 (图 1)。在单个实验室中生成的源取决于使用了24、25的质谱仪的接口。在这里, 建立基于商业 nanoESI 源 (图 2) 的 Sec nanoESI 源, 并实现台式四极 orbitrap 质谱仪。 注: 源的主体是一个立方不锈钢腔 (长度25毫米, id 13 毫米) (图 2b), 带有一个入口 (id 4 毫米), 将 nanoESI 毛细管引入腔室。因此, 会议厅未完全密封 (图 2b)。</li>
	<li>安装两个不锈钢管 (长度8毫米, 外径5毫米, id 3 毫米) 在房间的每一侧的气体输送。</li>
	<li>将两个石英窗 (14 毫米) 放在房间的顶部和底部, 以检查 nanoESI 毛细管和 nanoESI 喷雾尖端的位置, 无论是眼睛还是数码显微镜。</li>
	<li>将腔体焊接到质谱仪的扫锥上。 注: 设计可能会因个别实验室使用的质谱仪的大气压界面的特殊几何而改变。</li>
</ol>2. 仪器优化
<ol><li>根据制造商的指示, 在正负离子检测模式下校准质谱仪。通过应用标定, 将透镜电位和检测条件等质谱参数进行优化, 使灵敏度和峰值形状具有一定的分辨率值。70000的质量分辨率在这里使用。<ol>
<li>使用商用 ESI 源进行完全 Q Exactive 校准;但是, 可以使用任何兼容的源 (包括定制的) 进行质量校准。</li>
	</ol>
</li>
	<li>设置质谱仪 > 100 °c 的离子传输管 (ITT) 的温度。虽然最高温度可以设置在350摄氏度, 它可能会导致一些化合物的分解。因此, 在本实验中使用了150°c。 注: 对于具有取样孔而非 ITT 的质谱仪, 取样孔的温度设置 > 100 °c。</li>
	<li>对于 esi 溶剂和流量, 根据溶剂的性质 (例如、极性和挥发性) 和靶向化合物 (例如、质子亲和性) 选择适当的 esi 溶剂。水和甲醇的混合物在各种各样的比率被通常使用作为 ESI 溶剂25。在本实验中, 使用含 0.1% (v/v) 甲酸的水, 为高电离效率已报告此溶剂13,19,23。将 ESI 溶剂的流量设置在 0-1. 5 ul/分钟和 200 nL/分钟的范围内。 注: 加气 ESI 溶剂在使用前为30分钟。</li>
	<li>优化 nanoESI 源参数, 主要 nanoESI 电压和 nanoESI 毛细管尖端位置。电压通常从2.0 到4.5 伏不等。在这里使用2.5 伏。 注: 当流量增加时, 使用更高的 ESI 电压。刀尖与质谱孔之间的距离可由1到5毫米调整。优化后, 在质量谱中观测到的归一化强度级 (NL) 应为 > 1x106 , 而总离子色谱 (TIC) 在正负离子检测模式下的变化应为 < 10%。质量谱和 TIC 在m-/z 50-750 的质量范围内得到。</li>
	<li>将纯气体应用于源。这是一个可选的步骤, 旨在减少挥发性有机化合物对室内空气的影响。高纯度氮气 (N2, 99.99%) 或纯净的空气可以使用。在纯气体存在的情况下, 在质量谱中观测到的 NL 应为 > 1x105 , 在正负离子检测模式下, TIC 的变化应为 < 10%。此处使用高纯度 N2 , 并以0.8 升/分交货。 注: 纯气和呼吸气体的总流量应高于通过质谱管孔的流速。</li>
</ol>3. 呼出呼气的测量
<ol><li>吸入室内空气并进行正常呼气, 以恒定的流速呼出肺部的空气。通过压力计或流量计对该主题可见的流量表监视呼气流速。使用聚四氟乙烯 (PTFE) 油管输送呼吸气体23。<ol>
<li>为防止管道内的水蒸气凝结, 请在80-100 oC7、23、27或使用 Nafion 烘干机2829的温度下加热油管。在本实验中, 该主题以流量计控制的0.4 升/分呼出。</li>
		<li>将流量计的入口连接到 Nafion 油管 (长度60厘米), 以除去呼出的呼吸中的水蒸气, 并将流量计的出口连接到聚四氟乙烯油管 (长度13厘米, id 4 毫米)。它采取 < 三十年代为一呼气测量。</li>
		<li>执行4-6 个复制的测量28,29。</li>
		<li>为了尽量减少混淆效果, 请让参与者在测量23之前至少30分钟进食、饮用和刷牙。 注: 为了尽量减少挥发性有机化合物对室内空气的影响, 据报道, 它吸入纯气体而不是室内空气26。当使用 Nafion 油管时, 一些极性化合物可能会丢失。</li>
		<li>在测量过程中, 要检查离子强度是否超过仪器的线性检测极限。信号的饱和可能导致工件的峰值, 这实际上不是由样品中的化合物产生的。通过鼻子吸入, 部分环境挥发性有机化合物和微粒将被去除;然而, 值得注意的是, 鼻腔通道中的化合物也可能被检测到。</li>
	</ol>
</li>
</ol>4. 获得一个呼吸指纹和一个化合物的时间痕迹
<ol><li>获得图谱和质谱。使用软件 (如 Xcalibur) 记录图谱和质谱。由于这是直接的 MS 分析和不进行色谱分离, 总离子色谱 (TIC) 实际上表明了在质谱中检测到的所有信号的时间迹, 提取的离子色谱 (EIC) 显示了一个指定的化合物。 注: 对于其他商用质谱仪, 可通过相应的数据采集软件获得图谱和质量谱。</li>
	<li>当测量呼出的呼吸时, 在 TIC 中选择一些扫描, 获得呼出的呼吸指纹。获得一个质量频谱, 代表这些扫描的平均值由软件。<ol>
<li>要消除呼吸指纹的背景峰值, 请使用软件中的减法背景工具。请参阅制造商提供的用户指南。简而言之, 在不引入呼吸样本的情况下, 选择相同数量的扫描, 并从呼吸指纹中减去背景质量谱。 注: 在该方法中, 确定呼吸指纹特征的阈值为背景信号的标准差的三倍。对于其他商用质谱仪, 可以通过相应的数据采集软件进行背景减法。</li>
	</ol>
</li>
	<li>获取指定化合物的时间迹。在呼吸指纹中选择目标化合物的峰值, 然后通过软件获取该化合物的时间迹。</li>
</ol>

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作者没有什么可透露的。

建立基于商业 nanoESI 源的 Sec-nanoESI 源, 其电离效率高于使用 ESI 源30。此外, 封闭腔内的电离效率进一步提高, 因为它将过程与环境背景空气隔离开来, 同时促进气体样品与喷雾羽流的混合。通过使用 Sec nanoESI, 相对于 ESI 源, 需要优化较少的参数, 从而便于安装、应用和维护。
如果 nanoESI-MS 进行呼吸分析时没有观察到信号或灵敏度显著下降, 应检查喷雾毛细管尖...

随着现代分析技术的飞速发展, 数以百计的挥发性有机化合物 (voc) 已经在人呼出的呼吸中发现了1。这些挥发气主要是由肺泡空气 (350 毫升为一个健康的成人) 和解剖死亡空间空气 (~ 150 毫升)2, 受身体新陈代谢的影响3,4,5,6,7 ,8和环境污染9分别。因此, 如果确定, 这些挥发性有机化合物有望被用作疾病诊断和环境暴露的生物标志物。
气相色谱质谱法 (gc-ms) 是对呼出挥发性有机化合物进行定性定量分析的最广泛应用的技术2, 直接 MS 技术已经发展为实时呼吸分析, 具有高的时间分辨率和简单的样品预准备。直接 MS 技术, 如质子转移反应 ms (PTR)10, 选定的离子流管 ms (筛-ms)11, 二次电喷雾电离 ms (局)12,13 (也命名为萃取电喷雾电离 ms, EESI14,15), 微量大气气体分析仪 (TAGA)16和等离子电离 ms (PI-毫秒)17已被调查近年来。
在所有的直接 MS 技术中, 局是众所周知的通用软电离技术19,20,21;源很容易被定制, 并结合到不同类型的质谱仪,例如, 飞行质量光谱仪的时间8,15, 离子阱质谱仪14和 orbitrap 质谱仪12 ,18。到目前为止, 局已成功地用于诊断呼吸系统疾病22, 测量昼夜节律3,6,23, 药代动力学7,8, 和揭示代谢通路4,等。最近, 一个商业局源已成为可用。
在本研究中, 建立了一种轻便紧凑的二次 nanoelectrospray 电离源 (Sec nanoESI), 并将其耦合到高分辨率质谱仪中。对呼出的挥发性有机化合物进行了实时测量。

<table><tbody><tr><td>Ultrapure water</td><td>Merck Millipore, USA</td><td>MPGP04001</td><td>Resistance &gt;18.2 M&amp;Omega;&amp;middot;cm</td></tr><tr><td>Formic acid</td><td>Sigma-Aldrich, USA</td><td>F0507</td><td>Corrosive to the respiratory tract.</td></tr><tr><td>Nitrogen gas</td><td>Guangzhou Shiyuan Gas Co. Ltd., China</td><td>N.A.&lt;sup&gt;a&lt;/sup&gt;</td><td>Purity &gt;99.99%</td></tr><tr><td>Q Exactive hybrid quadrupole-orbitrap mass spectrometer</td><td>Thermo Scientific, USA</td><td>02634L(S/N)</td><td>Beware of high voltage and high temperature</td></tr><tr><td>NanoESI source</td><td>Thermo Scientific, USA</td><td>ES002373(S/N); ES071(P/N)</td><td>Beware of high voltage and high temperature</td></tr><tr><td>Nano LC pump</td><td>Thermo Scientific, USA</td><td>5041.0010A(P/N)</td><td>/</td></tr><tr><td>Xcalibur software (Version 3.0)</td><td>Thermo Scientific, USA</td><td>BRE0008596</td><td>/</td></tr><tr><td>Dino-Lite Digital Microscope</td><td>Tech Video System (SuZhou) Co.Ltd., China</td><td>CQ401833R(S/N)</td><td>/</td></tr><tr><td>Nafion tubing</td><td>Perma Pure LLC, USA</td><td>ME60</td><td>/</td></tr><tr><td>PTFE tubing (I.D. 4 mm)</td><td>Dongguan Hongfu Insulating Material Co. Ltd., China</td><td>N.A.</td><td>Beware of the possible loss of polar compounds</td></tr><tr><td>Mass flow controller</td><td>Line-Tech, Korea</td><td>M15122007 (S/N)</td><td>/</td></tr><tr><td>Flow meter</td><td>Yuyao Industrial Automation Meter Factory, China</td><td>40784</td><td>/</td></tr><tr><td>&lt;sup&gt;a&lt;/sup&gt;N.A.: not available.</td><td></td><td></td><td></td></tr></tbody></table>

real-time breath analysis by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry

呼出挥发性有机化合物 (voc) 引起了相当大的兴趣, 因为它们可以作为疾病诊断和环境暴露的生物标志物, 以无创的方式。在这项工作中, 我们提出了一个协议, 用二次 nanoelectrospray 电离耦合到高分辨率质谱 (Sec-nanoESI-HRMS) 实时表征呼出的挥发性有机化合物。自制的 Sec nanoESI 源很容易建立在商业 nanoESI 的基础上。在呼气的背景下减去的质谱中观察到数以百计的峰值, 其质量准确度分别为正负离子检测模式的 4.0-13.5 ppm 和-20.3-1.3 ppm。根据精确的质量和同位素模式, 对峰进行了精确的元素组成。少于三十年代用于一次呼气测量, 并且它需要大约7分钟为六个被复制的测量。

图 3显示了在正负离子检测模式下记录的m/z 50-750 的质量范围内的呼吸指纹。分别在正负离子检测模式下, 观察了291峰 (峰值强度 > 5.0x104) 和173峰值 (峰值强度 > 3.0x104)。要识别质量谱中的峰值, 请参阅以前发布的详细信息12,18,24,29。?...

Watch this Scientific Journal Video about Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry at JoVE.com

Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry

本文证明了用二次 nanoelectrospray 电离耦合高分辨质谱法对呼气的化学成分进行实时表征的一种协议。

利用二次 Nanoelectrospray 电离耦合高分辨质谱的实时呼吸分析

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental ...

real-time-breath-analysis-using-secondary-nanoelectrospray-ionization

Research

JoVE Journal

Chemistry

8.8K 次观看.  Jinan University. 本文证明了用二次 nanoelectrospray 电离耦合高分辨质谱法对呼气的化学成分进行实时表征的一种协议。

视频: Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS)

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first separated into polar and non-polar fractions by a liquid-liquid phase extraction, and partially purified to facilitate downstream analysis. Both aqueous (polar metabolites) and organic (non-polar metabolites) phases of the initial extraction are processed to survey a broad range of metabolites. Metabolites are separated by different liquid chromatography methods based upon their partition properties. In this method, we present microflow ultra-performance (UP)LC methods, but the protocol is scalable to higher flows and lower pressures. Introduction into the mass spectrometer can be through either general or compound optimized source conditions. Detection of a broad range of ions is carried out in full scan mode in both positive and negative mode over a broad m/z range using high resolution on a recently calibrated instrument. Label-free differential analysis is carried out on bioinformatics platforms. Applications of this approach include metabolic pathway screening, biomarker discovery, and drug development.

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry UPLC-HRMS

Untargeted metabolomics provides a hypothesis generating snapshot of a metabolic profile. This protocol will demonstrate the extraction and analysis of metabolites from cells, serum, or tissue. A range of metabolites are surveyed using liquid-liquid phase extraction, microflow ultraperformance liquid chromatography/high-resolution mass spectrometry (UPLC-HRMS) coupled to differential analysis software.

不相关的代谢组学，生物源使用超高效液相色谱 - 高分辨质谱（UPLC-HRMS）

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first ...

科研

化学

Characterizing Bacterial Volatiles using Secondary Electrospray Ionization Mass Spectrometry (SESI-MS)

Secondary electrospray ionization mass spectrometry (SESI-MS) is a method developed for the rapid detection of volatile compounds, without the need for sample pretreatment. The method was first described by Fenn and colleagues1 and has been applied to the detection of illicit drugs2 and explosives3-4, the characterization of skin volatiles5, and the analysis of breath6-7.
SESI ionization occurs by proton transfer reactions between the electrospray solution and the volatile analyte, and is therefore suitable for the analysis of hetero-organic molecules, just as in traditional electrospray ionization (ESI). However, unlike standard ESI, the proton transfer process of SESI occurs in the vapor phase rather than in solution (Fig. 1), and therefore SESI is best suited for detecting organic volatiles and aerosols.
We are expanding the use of SESI-MS to the detection of bacterial volatiles as a method for bacterial identification and characterization8. We have demonstrated that SESI-MS volatile fingerprinting, combined with a statistical analysis method, can be used to differentiate bacterial genera, species, and mixed cultures in a variety of growth media.8 Here we provide the steps for obtaining bacterial volatile fingerprints using SESI-MS, including the instrumental parameters that should be optimized to ensure robust bacterial identification and characterization.

Characterizing Bacterial Volatiles using Secondary Electrospray Ionization Mass Spectrometry SESI-MS

Secondary electrospray ionization mass spectrometry (SESI-MS) enables the detection of volatile organic compounds (VOCs) without the need for any sample pretreatment. This protocol provides instructions for the rapid (within minutes) characterization of bacterial VOCs using SESI-MS.

使用辅助电喷雾质谱（SESI - MS）表征细菌挥发

Secondary electrospray ionization mass spectrometry (SESI-MS) is a method developed for the rapid detection of volatile compounds, without the need for ...

生物工程

PTR-ToF-MS Coupled with an Automated Sampling System and Tailored Data Analysis for Food Studies: Bioprocess Monitoring, Screening and Nose-space Analysis

Proton Transfer Reaction (PTR), combined with a Time-of-Flight (ToF) Mass Spectrometer (MS) is an analytical approach based on chemical ionization that belongs to the Direct-Injection Mass Spectrometric (DIMS) technologies. These techniques allow the rapid determination of volatile organic compounds (VOCs), assuring high sensitivity and accuracy. In general, PTR-MS requires neither sample preparation nor sample destruction, allowing real time and non-invasive analysis of samples. PTR-MS are exploited in many fields, from environmental and atmospheric chemistry to medical and biological sciences. More recently, we developed a methodology based on coupling PTR-ToF-MS with an automated sampler and tailored data analysis tools, to increase the degree of automation and, consequently, to enhance the potential of the technique. This approach allowed us to monitor bioprocesses (e.g. enzymatic oxidation, alcoholic fermentation), to screen large sample sets (e.g. different origins, entire germoplasms) and to analyze several experimental modes (e.g. different concentrations of a given ingredient, different intensities of a specific technological parameter) in terms of VOC content. Here, we report the experimental protocols exemplifying different possible applications of our methodology: i.e. the detection of VOCs released during lactic acid fermentation of yogurt (on-line bioprocess monitoring), the monitoring of VOCs associated with different apple cultivars (large-scale screening), and the in vivo study of retronasal VOC release during coffee drinking (nosespace analysis).

Proton Transfer Reaction Time of Flight Mass Spectrometry allows high-sensitivity, rapid and non-invasive analysis of volatile organic compounds. To demonstrate its potential, we give three examples: lactic acid fermentation of yogurt (on-line bioprocess monitoring), different apple genotypes (large-scale screening), and retronasal space after drinking coffee (nosespace analysis).

PTR-ToF-MS结合自动采样系统和食品研究定制数据分析:生物过程监测，筛选和鼻空间分析

Proton Transfer Reaction (PTR), combined with a Time-of-Flight (ToF) Mass Spectrometer (MS) is an analytical approach based on chemical ionization that ...

Leaf Spray Mass Spectrometry: A Rapid Ambient Ionization Technique to Directly Assess Metabolites from Plant Tissues

Plants produce thousands of small molecules that are diverse in their chemical properties. Mass spectrometry (MS) is a powerful technique for analyzing plant metabolites because it provides molecular weights with high sensitivity and specificity. Leaf spray MS is an ambient ionization technique where plant tissue is used for direct chemical analysis via electrospray, eliminating chromatography from the process. This approach to sampling metabolites allows for a wide range of chemical classes to be detected simultaneously from intact plant tissues, minimizing the amount of sample preparation needed. When used with a high-resolution, accurate mass MS, leaf spray MS facilitates the rapid detection of metabolites of interest. It is also possible to collect tandem mass fragmentation data with this technique to facilitate a compound identification. The combination of accurate mass measurements and fragmentation is beneficial in confirming compound identities. The leaf spray MS technique requires only minor modifications to a nanospray ionization source and is a useful tool to further expand the capabilities of a mass spectrometer. Here, fresh leaf tissue from Sceletium tortuosum (Aizoaceae), a traditional medicinal plant from South Africa, is analyzed; numerous mesembrine alkaloids are detected with leaf spray MS.

Leaf spray mass spectrometry is a direct chemical analysis technique that minimizes the sample preparation and eliminates chromatography, allowing for the rapid detection of small molecules from plant tissues.

叶喷雾质谱: 一种快速的环境电离技术直接评价植物组织中的代谢产物

Plants produce thousands of small molecules that are diverse in their chemical properties. Mass spectrometry (MS) is a powerful technique for analyzing ...

生物化学

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Fizzy extraction is a new laboratory technique for analysis of volatile and semivolatile compounds. A carrier gas is dissolved in the liquid sample by applying overpressure and stirring the sample. The sample chamber is then decompressed. The analyte species are liberated to the gas phase due to effervescence.

挥发性有机化合物与大气压化学电离四极杆质谱联用

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

Sample Preparation for Probe Electrospray Ionization Mass Spectrometry

Mass spectrometry (MS) is a powerful tool in analytical chemistry because it provides very accurate information about molecules, such as mass-to-charge ratios (m/z), which are useful to deduce molecular weights and structures. While it is essentially a destructive analytical method, recent advancements in the ambient ionization technique have enabled us to acquire data while leaving tissue in a relatively intact state in terms of integrity. Probe electrospray ionization (PESI) is a so-called direct method because it does not require complex and time-consuming pretreatment of samples. A fine needle serves as a sample picker, as well as an ionization emitter. Based on the very sharp and fine property of the probe tip, destruction of the samples is minimal, allowing us to acquire the real-time molecular information from living things in situ. Herein, we introduce three applications of PESI-MS technique that will be useful for biomedical research and development. One involves the application to solid tissue, which is the basic application of this technique for the medical diagnosis. As this technique requires only 10 mg of the sample, it may be very useful in the routine clinical settings. The second application is for in vitro medical diagnostics where human blood serum is measured. The ability to measure fluid samples is also valuable in various biological experiments where a sufficient volume of sample for conventional analytical techniques cannot be provided. The third application leans toward the direct application of probe needles in living animals, where we can obtain real-time dynamics of metabolites or drugs in specific organs. In each application, we can infer the molecules that have been detected by MS or use artificial intelligence to obtain a medical diagnosis.

This article introduces sample preparation methods for a unique real-time analytical method based on the ambient mass spectrometry. This method lets us perform real-time analysis of the biological molecules in vivo without any special pretreatments.

探头电喷电镀质谱的样品制备

Mass spectrometry (MS) is a powerful tool in analytical chemistry because it provides very accurate information about molecules, such as mass-to-charge ...

Breath Collection from Children for Disease Biomarker Discovery

Breath collection and analysis can be used to discover volatile biomarkers in a number of infectious and non-infectious diseases, such as malaria, tuberculosis, lung cancer, and liver disease. This protocol describes a reproducible method for sampling breath in children and then stabilizing breath samples for further analysis with gas chromatography-mass spectrometry (GC-MS). The goal of this method is to establish a standardized protocol for the acquisition of breath samples for further chemical analysis, from children aged 4-15 years. First, breath is sampled using a cardboard mouthpiece attached to a 2-way valve, which is connected to a 3 L bag. Breath analytes are then transferred to a thermal desorption tube and stored at 4-5 &#176;C until analysis. This technique has been previously used to capture breath of children with malaria for successful breath biomarker identification. Subsequently, we have successfully applied this technique to additional pediatric cohorts. The advantage of this method is that it requires minimal cooperation on part of the patient (of particular value in pediatric populations), has a short collection period, does not require trained staff, and can be performed with portable equipment in resource-limited field settings.

This protocol describes a simple method for the acquisition of breath samples from children. Briefly, samples of mixed air are pre-concentrated in sorbent tubes prior to gas chromatography-mass spectrometry analysis. Breath biomarkers of infectious and non-infectious diseases can be identified using this breath collection method.

儿童疾病生物标志物发现的呼吸收集

Breath collection and analysis can be used to discover volatile biomarkers in a number of infectious and non-infectious diseases, such as malaria, ...

Fast and Accurate Exhaled Breath Ammonia Measurement

This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. 
Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. 
The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations.

Ammonia is an important physiologic metabolite relevant to various disease and wellness states. It is also a difficult molecule to measure in breath, which demands particular precautions be taken to obtain accurate results. Not all factors influencing ammonia are known, but progress can be difficult without accounting for these factors.

快速，准确的呼出气测量氨

This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that ...

医学

Versatile Dual-Inlet Sample Introduction System for Multi-Mode Single Particle Inductively Coupled Plasma Mass Spectrometry Analysis and Validation

Metal-containing nanoparticles (NP) can be characterized with inductively coupled plasma mass spectrometers (ICP-MS) in terms of their size and number concentration by using the single-particle mode of the instrument (spICP-MS). The accuracy of measurement depends on the setup, operational conditions of the instrument and specific parameters that are set by the user. The transport efficiency of the ICP-MS is crucial for the quantification of the NP and usually requires a reference material with homogenous size distribution and a known particle number concentration.
Currently, NP reference materials are available for only a few metals and in limited sizes. If particles are characterized without a reference standard, the results of both size and particle number may be biased. Therefore, a dual-inlet setup for characterizing nanoparticles with spICP-MS was developed to overcome this problem. This setup is based on a conventional introduction system consisting of a pneumatic nebulizer (PN) for nanoparticle solutions and a microdroplet generator (&#181;DG) for ionic calibration solutions. A new and flexible interface was developed to facilitate the coupling of &#181;DG, PN and the ICP-MS system. The interface consists of available laboratory components and allows for the calibration, nanoparticle (NP) characterization and cleaning of the arrangement, while the ICP-MS instrument is still running.
Three independent analysis modes are available for determining particle size and number concentration. Each mode is based on a different calibration principle. While mode I (counting) and mode III (&#181;DG) are known from the literature, mode II (sensitivity), is used to determine the transport efficiency by inorganic ionic standard solutions only. It is independent of NP reference materials. The &#181;DG based inlet system described here guarantees superior analyte sensitivities and, therefore, lower detection limits (LOD). The size dependent LODs achieved are less than 15 nm for all NP (Au, Ag, CeO2) investigated.

Here we provide a protocol for the use of a dual-inlet system for single particle inductively coupled mass spectrometry which allows for a standard independent nanoparticle characterization.

Metal-containing nanoparticles (NP) can be characterized with inductively coupled plasma mass spectrometers (ICP-MS) in terms of their size and number ...

Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry

Ambient ionization methods in mass spectrometry allow analytical investigations to be performed directly on a tissue or biofilm under native-like experimental conditions. Laser ablation electrospray ionization (LAESI) is one such development and is particularly well-suited for the investigation of water-containing specimens. LAESI utilizes a mid-infrared laser beam (2.94 &mu;m wavelength) to excite the water molecules of the sample. When the ablation fluence threshold is exceeded, the sample material is expelled in the form of particulate matter and these projectiles travel to tens of millimeters above the sample surface. In LAESI, this ablation plume is intercepted by highly charged droplets to capture a fraction of the ejected sample material and convert its chemical constituents into gas-phase ions. A mass spectrometer equipped with an atmospheric-pressure ion source interface is employed to analyze and record the composition of the released ions originating from the probed area (pixel) of the sample. A systematic interrogation over an array of pixels opens a way for molecular imaging in the microprobe analysis mode. A unique aspect of LAESI mass spectrometric imaging is depth profiling that, in combination with lateral imaging, enables three-dimensional (3D) molecular imaging. With current lateral and depth resolutions of ~100 &mu;m and ~40 &mu;m, respectively, LAESI mass spectrometric imaging helps to explore the molecular structure of biological tissues. Herein, we review the major elements of a LAESI system and provide guidelines for a successful imaging experiment.

Laser ablation electrospray ionization (LAESI) is an atmospheric-pressure ion source for mass spectrometry. In the imaging mode, a mid-infrared laser probes the distributions of molecules across a tissue section or a biofilm. This technique presents a new approach for diverse bioanalytical studies carried out under native experimental conditions.