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 &#62;18.2 M&#937;&#183;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.a</td>
			<td>Purity &#62;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>aN.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

A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry

In this study we evaluated a method for the characterization of complexes, formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptide, by electrospray ionization orbitrap mass spectrometry. This strategy is based on previous successful characterization of mercury-dicysteinyl complexes involving tripeptides by utilizing mass spectrometry among other techniques. Mercury(II) chloride and a dicysteinyl tetrapeptide were incubated in a degassed buffered medium at varying stoichiometric ratios. The complexes formed were subsequently analyzed on an electrospray mass spectrometer consisting of a hybrid linear ion- and orbi- trap mass analyzer. The electrospray ionization mass spectrometry (ESI-MS) spectra were acquired in the positive mode and the observed peaks were then analyzed for distinct mercury isotopic distribution patterns and associated monoisotopic peak. This work demonstrates that an accurate stoichiometry of mercury and peptide in the complexes formed under specified electrospray ionization conditions can be determined by using high resolution ESI MS based on distinct mercury isotopic distribution patterns.

A Study of the Complexation of MercuryII with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry

The characterization of complexes formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptides by electrospray ionization orbitrap mass spectrometry is presented.

汞（II）与Dicysteinyl四肽的络合的电喷雾质​​谱研究

In this study we evaluated a method for the characterization of complexes, formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptide, ...

Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, and that these chemical fingerprints can be used for plant species identification. The mass spectral data can be acquired rapidly and in a high throughput manner without the need for sample extraction, derivatization or pH adjustment steps. The use of this technique bypasses challenges presented by more conventional techniques including lengthy chromatography analysis times and resource intensive methods. The high throughput capabilities of the direct analysis in real time-high resolution mass spectrometry protocol, coupled with multivariate statistical analysis processing of the data, provide not only class characterization of plants, but also yield species and varietal information. Here, the technique is demonstrated with two psychoactive plant products, Mitragyna speciosa (Kratom) and Datura (Jimsonweed), which were subjected to direct analysis in real time-high resolution mass spectrometry followed by statistical analysis processing of the mass spectral data. The application of these tools in tandem enabled the plant materials to be rapidly identified at the level of variety and species.

A method for species identification of botanical material by direct analysis in real time-high resolution mass spectrometry and multivariate statistical analysis is presented.

植物材料的快速高通量物种鉴定实时高分辨质谱法直接分析

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, ...

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 ...

Synthesis and Mass Spectrometry Analysis of Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have been thought of as a type of molecular information storage. Mass spectrometry analysis has been considered the method of choice for sequencing peptoids. Peptoids can be synthesized via solid phase chemistry using a repeating two-step reaction cycle. Here we present a method to manually synthesize oligo-peptoids and to analyze the sequence of the peptoids using tandem mass spectrometry (MS/MS) techniques. The sample peptoid is a nonamer consisting of alternating N-(2-methyloxyethyl)glycine (Nme) and N-(2-phenylethyl)glycine (Npe), as well as an N-(2-aminoethyl)glycine (Nae) at the N-terminus. The sequence formula of the peptoid is Ac-Nae-(Npe-Nme)4-NH2, where Ac is the acetyl group. The synthesis takes place in a commercially available solid-phase reaction vessel. The rink amide resin is used as the solid support to yield the peptoid with an amide group at the C-terminus. The resulting peptoid product is subjected to sequence analysis using a triple-quadrupole mass spectrometer coupled to an electrospray ionization source. The MS/MS measurement produces a spectrum of fragment ions resulting from the dissociation of charged peptoid. The fragment ions are sorted out based on the values of their mass-to-charge ratio (m/z). The m/z values of the fragment ions are compared against the nominal masses of theoretically predicted fragment ions, according to the scheme of peptoid fragmentation. The analysis generates a fragmentation pattern of the charged peptoid. The fragmentation pattern is correlated to the monomer sequence of the neutral peptoid. In this regard, MS analysis reads out the sequence information of the peptoids.

A protocol is described for the manual synthesis of oligo-peptoids followed by sequence analysis by mass spectrometry.

寡 peptoids 的合成及质谱分析

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have ...

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) Mass Spectrometry

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

A protocol for the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) characterization of synthetic polymers is described including the optimization of sample preparation, spectral acquisition, and data analysis.

基质辅助激光解吸电离飞行时间 (MALDI) 质谱法表征合成聚合物

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group ...

An Efficient Sample Preparation Method to Enhance Carbohydrate Ion Signals in Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

Sample preparation is a critical process in mass spectrometry (MS) analysis of carbohydrates. Although matrix-assisted laser desorption/ionization (MALDI) MS is the method of choice in carbohydrate analysis, poor ion signal and data reproducibility of carbohydrate samples continue to be severe problems. For quantitative analysis of carbohydrates, an effective analytical protocol providing superior data quality is necessary. This video demonstrates sample preparation protocols to improve signal intensity and minimize data variation of carbohydrates in MALDI-MS. After drying and crystallization of sample droplets, the crystal morphology is reformed by methanol before mass spectrometric analysis. The enhancement in carbohydrate signal is examined with MALDI imaging mass spectrometry (IMS). Experimental results show that crystal reformation adjusts crystalline structures and redistributes carbohydrate analytes. In comparison with the dried droplet preparation method in conventional MALDI-MS, reforming carbohydrate crystal morphologies with methanol shows significantly better signal intensity, ion image distribution, and data stability. Since the protocols demonstrated herein do not involve changes in sample composition, they are generally applicable to various carbohydrates and matrixes.

A protocol for enhancing carbohydrate ion signals in MALDI mass spectrometry by reforming crystalline structures during sample preparation processes is demonstrated.

基质辅助激光解吸/电离质谱中增强碳水化合物离子信号的高效样品制备方法

Sample preparation is a critical process in mass spectrometry (MS) analysis of carbohydrates. Although matrix-assisted laser desorption/ionization (MALDI) ...

High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry

New analytical methods are urgently needed to enable high-throughput, yet comprehensive drug screening, given an alarming opioid and prescription drug crisis in public health. Conventional urine drug testing based on a two-tier immunoassay screen followed by a gas chromatography-tandem mass spectrometry (GC-MS/MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) method are expensive and prone to bias while being limited to targeted panels of known drugs of abuse (DoA). Herein, we outline an improved method for drug surveillance that allows for the resolution and detection of an expanded panel of DoA and their metabolites when using multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). Multiplexed separations of ten urine samples with a quality control by CE (&lt; 3 min/sample) in conjunction with full-scan data acquisition using a time-of-flight mass spectrometer (TOF-MS) under positive ion mode detection allows for the identification and quantification of DoA above recommended cut-off levels. An excellent resolution of drug isomers and isobars, including background interferences, are achieved when using MSI-CE-MS with an electrokinetic spacer between sample segments, where accurate mass/molecular formula together with the comigration of a matching deuterated internal standard and the detection of one or more bio-transformed metabolites facilitate DoA identification over a wider detection window. Additionally, urine samples can be analyzed directly without enzyme deconjugation for the rapid screening without complicated sample workup. MSI-CE-MS enables the surveillance of a broad spectrum of DoA that is required for the treatment monitoring of high-risk patients, including confirming prescribed drug adherence, revealing illicit drug use/substitution, and evaluating optimal dosage regimes as required for new advances in precision medicine.

Here we describe a high-throughput method for comprehensive drug surveillance that allows for the improved resolution and detection of large panels of drugs of abuse and their metabolites, with quality control based on multisegment injection-capillary electrophoresis-mass spectrometry.

采用多段注射-毛细管电泳质谱法进行高通量和综合药物监测

New analytical methods are urgently needed to enable high-throughput, yet comprehensive drug screening, given an alarming opioid and prescription drug ...

Imaging Corrosion at the Metal-Paint Interface Using Time-of-Flight Secondary Ion Mass Spectrometry

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), illustrating that SIMS is a suitable technique to study the chemical distribution at a metal-paint interface. The painted Al alloy coupons are immersed in a salt solution or exposed to air only. SIMS provides chemical mapping and 2D molecular imaging of the interface, allowing direct visualization of the morphology of the corrosion products formed at the metal-paint interface and mapping of the chemical after corrosion occurs. The experimental procedure of this method is presented to provide technical details to facilitate similar research and highlight pitfalls that may be encountered during such experiments.

Time-of-flight secondary ion mass spectrometry is applied to demonstrate the chemical mapping and corrosion morphology at the metal-paint interface of an aluminum alloy after being exposed to a salt solution compared with a specimen exposed to air.

利用飞行时二次离子质谱法成像金属颜料界面的腐蚀

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass ...

Analysis of Complex Molecules and Their Reactions on Surfaces by Means of Cluster-Induced Desorption/Ionization Mass Spectrometry

Desorption/Ionization Induced by Neutral SO2 Clusters (DINeC) is employed as a very soft and efficient desorption/ionization technique for mass spectrometry (MS) of complex molecules and their reactions on surfaces. DINeC is based on a beam of SO2 clusters impacting on the sample surface at low cluster energy. During cluster-surface impact, some of the surface molecules are desorbed and ionized via dissolvation in the impacting cluster; as a result of this dissolvation-mediated desorption mechanism, low cluster energy is sufficient and the desorption process is extremely soft. Both surface adsorbates and molecules of which the surface is composed of can be analyzed. Clear and fragmentation-free spectra from complex molecules such as peptides and proteins are obtained. DINeC does not require any special sample preparation, in particular no matrix has to be applied. The method yields quantitative information on the composition of the samples; molecules at a surface coverage as low as 0.1 % of a monolayer can be detected. Surface reactions such as H/D exchange or thermal decomposition can be observed in real-time and the kinetics of the reactions can be deduced. Using a pulsed nozzle for cluster beam generation, DINeC can be efficiently combined with ion trap mass spectrometry. The matrix-free and soft nature of the DINeC process in combination with the MSn capabilities of the ion trap allows for very detailed and unambiguous analysis of the chemical composition of complex organic samples and organic adsorbates on surfaces.

Neutral SO2 clusters of low kinetic energy (&#60; 0.8 eV/constituent) are used to desorb complex surface molecules such as peptides or lipids for further analysis by means of mass spectrometry using an ion trap mass spectrometer. No special sample preparation is required, and real-time observation of reactions is possible.