我们要感谢台湾科技部（拨款号:第104-2628-M-009-003-MY4号），为这项工作提供财政支持。

该协议假定所有步骤均按照相关的实验室安全规定进行。一些步骤使用商业手段 - 在这种情况下，需要遵循制造商的指导原则。处理有毒化学物质时，必须遵守MSDS的指导原则。定制设备4必须谨慎操作;特别是在处理加压气体和带电电线时。 1.准备标准溶液<ol><li>通过将10μL柠檬烯与990μL乙醇混合，制备6.2×10 -2 M柠檬烯储存在乙醇中的溶液。 </li><li>通过混合10μL6.2 x 10 -2柠檬烯，490μL乙醇和加入纯水至终体积为10 mL，制备10 mL 6.2 x 10 -5 M柠檬烯溶液。彻底摇匀容量瓶。 </li><li>将准备的标准溶液转移到具有隔垫的20-mL螺旋顶部顶空玻璃小瓶中米帽稀释的标准溶液可用于测试系统。 </li></ol> 2.准备样品<ol><li>通过在厨房挤压器上挤压新鲜的酸橙水果（切成两半）来获得酸橙汁。 </li><li>通过混合2 mL柠檬汁，500μL乙醇和加入纯水至最终体积为10 mL准备10 mL稀柠檬汁。彻底摇匀容量瓶。 </li><li>将准备的样品转移到具有隔垫帽的20-mL螺旋顶部顶空玻璃小瓶中。 </li></ol> 3.用标准解决方案填充真实样品<ol><li>第一标准添加:通过混合2 mL柠檬汁，10μL6.2 x 10 -2 M柠檬烯溶液，490μL乙醇，并加入纯水至终体积为10 mL，准备10 mL加标样品。彻底摇匀容量瓶。 </li><li>第二标准添加:通过混合2 mL柠檬汁，20μL6.2 x 10 -2 M柠檬酸制备10 mL加标样品e溶液，480μL乙醇，并加入纯水至终体积为10mL。彻底摇匀容量瓶。 </li></ol> 4.设置雾化提取系统<ol><li>将闪烁提取系统（ 图1 ） 4放在三重四极杆质谱仪的APCI源旁边。 </li><li>将二氧化碳气瓶连接到气泡提取系统的供气口。打开气体调节器中的阀门。将输出压力设置为1.5 bar（150 kPa）。 </li><li>将提取室出口连接到离子源入口。 </li><li>将发泡系统连接到12 V电源。 </li><li> 设置三重四极杆质谱仪的数据采集软件 （ 图2 ）。 在正离子多反应监测（MRM）模式下，用氩气作为碰撞，用APCI光源操作仪器加油站。 <ol><li>运行数据采集软件。 </li><li>选择"仅LCMS8030"选项。 </li><li>选择选项"MS开/关"。 </li><li>设置去溶剂化温度线至250℃，和分钟-1干燥气体至15升的流量。等待每个仪器参数的值与预设值相同。 </li><li>选择MS数据采集方法文件。 </li><li>确保碰撞电压为-20 V，前体离子m / z为137，碎片离子m / z为81和95 </li><li>点击"开始单次运行"按钮。 </li><li>键入文件名。 </li><li>选择文件路径。 </li><li>转到第5节（"进行泡沫提取"）。 </li><li>选择选项"MS开/关"。 </li><li>关闭软件窗口。 </li><li>勾选"雾化气体关闭"，"DL加热器关闭"，"热块关闭"和"干气关闭"。点击"确定"＃34 ;. </li></ol></li></ol> 5.进行气泡提取<ol><li>通过使用螺丝钉将样品瓶放入精油萃取系统。萃取系统在室温（〜25℃）下运行。 </li><li>按fizzy提取系统的LCD屏幕上的"开始"按钮。 </li><li>等待自动化嘶嘶声提取过程执行（ 图3 ）。观察三重四极杆质谱仪屏幕上离子信号的发展。 注意:自动执行以下步骤:样品顶空在60秒内用二氧化碳冲洗。样品在二十六秒钟内用二氧化碳加压。搅拌马达开启。样品减压形成多个气泡。在后期阶段，搅拌马达开启以增加起泡。 </li><li>取出（拧下）样品瓶。 </li><li>用纤维素组织擦拭样品搅拌轴。 </li><li>洗涤搅拌sp放入乙醇，再次用纤维素组织擦拭。 </li><li>该系统已准备好分析另一个样品（重复步骤5.1-5.6）。 </li><li>关闭电源。 </li><li>从离子源中断开发泡管。 </li><li>关闭气瓶的阀门，并断开气体管道。 </li></ol>数据分析<ol><li> 将三重四极杆质谱仪的数据采集软件的m / z 81的离子流输出到ASCII文件（ 图4 ）。 注意:在本演示中不使用m / z 95处的离子电流。 <ol><li>运行数据采集软件。选择"Postrun"选项。 </li><li>选择"选择项目（文件夹）"选项，然后选择数据文件。 </li><li>点击"文件"菜单，选择"导出数据"/"导出数据为ASCII"。 </li><li>选择 ＆＃34;输出文件"，并选择文件路径，选择"MS色谱图（MC）"。 </li></ol></li><li> 将原始数据集导入峰集成软件，并测量峰面积（ 图5 ）。设置:线性基线; HVL功能。 <ol><li>运行峰值集成软件。 </li><li>从"文件"菜单中选择"导入"选项。点击"是"按钮。 </li><li>选择X和Y列中的数据。点击"确定"按钮。选择"AutoFit Peaks I Residuals"选项。 </li><li>半自动适应提取峰。确保拟合曲线遵循实验数据点。选择"List Peak Estimates"列表。选择选项"ASCII编辑器"。 </li><li>将拟合结果复制到"剪贴板"。 </li></ol></li><li> 在数据分析软件中将测量的峰值区域输入电子表格（ 图6 ）。 &lt;OL&gt; <li>运行数据分析软件。 </li><li>输入X列中的浓度值和Y列中的峰面积值。从"Plot"菜单中选择"Symbol"/"Scatter"选项。从"分析"菜单中选择"调整"/"适合线性"选项。 </li></ol></li><li>根据以下公式计算稀释的真实样品中柠檬烯的浓度: <img alt="公式1" src="/files/ftp_upload/56008/56008eq1.jpg" /> 其中我是线性函数的截距，而S是斜率。 </li><li>基于以下公式计算原始实际样品（稀释前）中柠檬烯的浓度: <img alt="方程式2" src="/files/ftp_upload/56008/56008eq2.jpg" /> 其中DF是稀释因子（这里是5）。 </li></ol>

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作者没有什么可以披露的。

<html>一些聪明的方法来提供样品质谱仪在过去的三个十年中进行的研究，开发（ 例如 ，参考8，9，10，11，12，13，14）。这些研究的目标之一是简化样品的准备以进行分析。为了实现这一目标，引入了离子源设计的?...

在自然界和日常生活中观察到的各种现象与气液相平衡有关。二氧化碳在升高的压力下溶解在软和含酒精的饮料中。当一瓶这样的泡沫饮料打开时，压力下降，气泡冲向液面。在这种情况下，泡腾可改善饮料的感官特性。气泡的释放也是减压病（"弯"）的主要原因1 。由于突然的减压，气泡形成在潜水员身上。患有减压病的人在高压室治疗。 气泡在分析化学中有各种应用。值得注意的是，喷射方法依靠通过液体样品的气泡来提取挥发性化合物2 。例如，称为"吹扫闭合回路"的方法与气相色谱相结合，可以快速分析二次溶解的挥发物3 。虽然喷射可以随着时间的推移不断地提取挥发物，但它并不局限于空间或时间。释放的气相物种需要被捕获，并且在某些情况下通过应用温度程序或使用吸附剂来浓缩。因此，需要引入新的在线样品处理策略，这可以减少步骤的数量，同时在空间或时间上浓缩挥发性分析物。 为了解决从液体样品中提取挥发性化合物并进行在线分析的挑战，我们最近推出了"fizzy extract" 4 。这种新技术利用了泡腾现象。简而言之，通过施加超压并搅拌样品，首先将载气（这里是二氧化碳）溶解在样品中。然后，样品室突然减压。突然减压导致形成许多载气泡<html>在样品液体中。这些泡沫有助于将溶解的分析物质从液体释放到气相。释放的分析物立即转移到质谱仪，在时域产生信号。因为分析物种的释放被限制在短时间（几秒），所以时间信号具有高幅度和高的信噪比。 泡沫萃取过程中所涉及的压力非常低（约150 kPa） 4 ;远远低于超临界流体萃取5 （ 例如 ≥10MPa）。该技术不需要使用任何特殊的消耗品（色谱柱，墨盒）。只有少量的溶剂用于稀释和清洗。提取装置可以由具有中等技术技能的化学家使用广泛可用的部件组装4 ;例如，开源电子模块"&gt; 6,7。碳酸提取可耦合上线用装有大气压化学电离（APCI）接口。由于气相萃取液转移至离子源，碳酸提取的操作基本上不污染脆弱现代质谱仪部分质谱仪。 这个可视化实验文章的目的是指导观众在简单的分析任务中如何实施fizzy提取。虽然fizzy提取系统的核心是我们以前的报告4所述 ，但已经引入了几项改进措施，使操作更为直接。配有LCD屏幕屏蔽的微控制器已经并入系统中以实时显示键提取参数。所有功能都在微控制器脚本中编程，并且不再需要使用外部计算机来c控制提取系统。

<table><tbody><tr><td>Water</td><td>Fisher</td><td>W6212</td><td>Diluent</td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>32221-2.5L</td><td>Diluent</td></tr><tr><td>(R)-(+)-Limonene</td><td>Sigma-Aldrich</td><td>183164-100ML</td><td>Standard</td></tr><tr><td>Carbon dioxide</td><td>ChiaLung</td><td>n/a</td><td>Carrier gas</td></tr><tr><td>Cellulose tissue, Kimwipes Kimtech</td><td>Kimberly-Clark</td><td>34120</td><td>Used for cleaning</td></tr><tr><td>Triple quadrupole mass spectrometer</td><td>Shimadzu</td><td>LCMS-8030</td><td>Detection system</td></tr><tr><td>Atmospheric pressure chemical ionization interface</td><td>Shimadzu</td><td>Duis</td><td>Ion source</td></tr><tr><td>20-mL screw top headspace glass vial with septum cap</td><td>Thermo Fisher Scientific</td><td>D-52379</td><td>Sample vial</td></tr><tr><td>LabSolutions software</td><td>Shimadzu</td><td>n/a</td><td>version 5.82</td></tr><tr><td>PeakFit software</td><td>Systat Software</td><td>n/a</td><td>version 4.12</td></tr><tr><td>OriginPro software</td><td>OriginLab</td><td>n/a</td><td>version 8</td></tr></tbody></table>

fizzy extraction of volatile organic compounds combined with atmospheric pressure chemical ionization quadrupole mass spectrometry

溶解在液体样品中的挥发性和半挥发性化合物的化学分析可能具有挑战性。溶解的组分需要进入气相，并有效转移到检测系统。泡沫提取利用泡腾现象。首先，通过施加超压并搅拌样品，将载气（这里为二氧化碳）溶解在样品中。第二，样品室突然减压。减压导致在样品液体中形成许多载气泡。这些泡沫有助于将溶解的分析物质从液体释放到气相。释放的分析物立即转移到三重四极杆质谱仪的大气压化学电离界面。可离子化分析物种在时域中产生质谱信号。因为分析物质的释放发生在短时间内（几秒钟）onds），时间信号具有高幅度和高信噪比。然后，时间峰值的振幅和面积可以与经过精细提取的液体样品中的分析物的浓度相关联，这使得能够进行定量分析。泡沫提取的优点包括:简单，速度快，化学品（溶剂）使用有限。

开始时，使用标准解决方案测试嘶嘶声提取系统。随后，分析了标准样品和真实样品。提取事件的时间峰面积与经过精炼提取的液体样品中分析物的浓度相关，可进行定量分析。在这里，我们执行了双重标准添加，以演示该技术的定量能力（ 图7 ）。线性回归导致以下功能（ 图8 ）: <p class="jove_content" fo:keep-together.within-page="1...

Watch this Scientific Journal Video about Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry at JoVE.com

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

闪光提取是用于分析挥发性和半挥发性化合物的新的实验室技术。通过施加超压并搅拌样品将载气溶解在液体样品中。然后将样品室减压。分析物种由于发泡而释放到气相中。

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 ...

fizzy-extraction-volatile-organic-compounds-combined-with-atmospheric

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JoVE Journal

Analytical Chemistry

Chemistry

Unit 1

Mass Spectrometry Fragmentation Methods

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7.6K 次观看.  National Chiao Tung University. 闪光提取是用于分析挥发性和半挥发性化合物的新的实验室技术。通过施加超压并搅拌样品将载气溶解在液体样品中。然后将样品室减压。分析物种由于发泡而释放到气相中。 

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

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 ...

科研

生物工程

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX.

In this paper, a procedure for quantifying the mass transport parameters of chemicals in various materials is presented. This process involves employing an inverse-analysis based diffusion model to vapor emission profiles recorded by real-time, mass spectrometry in high vacuum.

一个反分析方法化工运输的油漆表征

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in ...

化学

Analysis of Volatile and Oxidation Sensitive Compounds Using a Cold Inlet System and Electron Impact Mass Spectrometry

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The analysis of volatile and oxidation sensitive compounds by mass spectrometry is not easily achieved, as all state-of-the-art mass spectrometric methods require at least one sample preparation step, e.g., dissolution and dilution of the analyte (electrospray ionization), co-crystallization of the analyte with a matrix compound (matrix-assisted laser desorption/ionization), or transfer of the prepared samples into the ionization source of the mass spectrometer, to be conducted under atmospheric conditions. Here, the use of a sample inlet system is described which enables the analysis of volatile metal organyls, silanes, and phosphanes using a sector field mass spectrometer equipped with an electron impact ionization source. All sample preparation steps and the sample introduction into the ion source of the mass spectrometer take place either under air-free conditions or under vacuum, enabling the analysis of compounds highly susceptible to oxidation. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes, which have to be handled using inert conditions, such as the Schlenk technique. The principle of operation is presented in this video.

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes which have to be handled using inert conditions, such as the Schlenk technique.

挥发和氧化敏感的化合物使用冷进气系统和电子轰击质谱分析

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The ...

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Trace explosive vapors of TNT and RDX collected on sorbent-filled thermal desorption tubes were analyzed using a programmed temperature desorption system coupled to GC with an electron capture detector. The instrumental analysis is combined with direct liquid deposition method to reduce sample variability and account for instrumentation drift and losses.

定量检测痕量爆炸物蒸气通过程序升温脱附 - 气相色谱 - 电子捕获检测器

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive ...

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 ...

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile organic carbons (VOCs), illustrating this with a titanium dioxide based catalyst, and the VOC 2-propanol. The protocol takes advantage of field asymmetric ion mobility spectroscopy (FAIMS), an analysis tool that is capable of continuously identifying and monitoring the concentration of VOCs such as 2-propanol and acetone at the ppb level. The continuous nature of FAIMS allows detailed kinetic analysis, and long-term reactions, offering a significant advantage over gas chromatography, a batch process traditionally used in air purification characterization. The use of FAIMS in photocatalytic air purification has only recently been used for the first time, and with the protocol illustrated here, the flexibility in allowing alternative VOCs and photocatalysts to be tested using comparable protocols offers a unique system to elucidate photocatalytic air purification reactions at low concentrations.

A protocol for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) model volatile organic carbons such as 2-propanol is described.

用场不对称离子迁移光谱法分析 2-丙醇在室内空气浓度中的光氧化作用

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile ...

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

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental exposure in a non-invasive manner. In this work, we present a protocol to characterize the exhaled VOCs in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry (Sec-nanoESI-HRMS). The homemade Sec-nanoESI source was readily set up based on a commercial nanoESI source. Hundreds of peaks were observed in the background-subtracted mass spectra of exhaled breath, and the mass accuracy values are -4.0-13.5 ppm and -20.3-1.3 ppm in the positive and negative ion detection modes, respectively. The peaks were assigned with accurate elemental composition according to the accurate mass and isotopic pattern. Less than 30 s is used for one exhalation measurement, and it takes approximately 7 min for six replicated measurements.

A protocol for characterizing chemical composition of exhaled breath in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry is demonstrated.

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 ...

Profiling Volatile Compounds in Blackcurrant Fruit using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry

There is an increasing interest in measuring volatile organic compounds (VOCs) emitted by ripe fruits for the purpose of breeding varieties or cultivars with enhanced organoleptic characteristics and thus, to increase consumer acceptance. High-throughput metabolomic platforms have been recently developed to quantify a wide range of metabolites in different plant tissues, including key compounds responsible for fruit taste and aroma quality (volatilomics). A method using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) is described here for the identification and quantification of VOCs emitted by ripe blackcurrant fruits, a berry highly appreciated for its flavor and health benefits.
Ripe fruits of blackcurrant plants (Ribes nigrum) were harvested and directly frozen in liquid nitrogen. After tissue homogenization to produce a fine powder, samples were thawed and immediately mixed with sodium chloride solution. Following centrifugation, the supernatant was transferred into a headspace glass vial containing sodium chloride. VOCs were then extracted using a solid-phase microextraction (SPME) fiber and a gas chromatograph coupled to an ion trap mass spectrometer. Volatile quantification was performed on the resulting ion chromatograms by integrating peak area, using a specific m/z ion for each VOC. Correct VOC annotation was confirmed by comparing retention times and mass spectra of pure commercial standards run under the same conditions as the samples. More than 60 VOCs were identified in ripe blackcurrant fruits grown in contrasting European locations. Among the identified VOCs, key aroma compounds, such as terpenoids and C6 volatiles, can be used as biomarkers for blackcurrant fruit quality. In addition, advantages and disadvantages of the method are discussed, including prospective improvements. Furthermore, the use of controls for batch correction and minimization of drift intensity have been emphasized.

A headspace solid-phase microextraction-gas-chromatography platform is described here for fast, reliable, and semi-automated volatile identification and quantification in ripe blackcurrant fruits. This technique can be used to increase knowledge about fruit aroma and to select cultivars with enhanced flavor for the purpose of breeding.

使用顶空固相微萃取与气相色谱-质谱联用分析黑醋栗果实中的挥发性化合物

There is an increasing interest in measuring volatile organic compounds (VOCs) emitted by ripe fruits for the purpose of breeding varieties or cultivars ...

生物化学

Capturing Actively Produced Microbial Volatile Organic Compounds from Human-Associated Samples with Vacuum-Assisted Sorbent Extraction

Volatile organic compounds (VOCs) from biological samples have unknown origins. VOCs may originate from the host or different organisms from within the host&#39;s microbial community. To disentangle the origin of microbial VOCs, volatile headspace analysis of bacterial mono- and co-cultures of Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii, and stable isotope probing in biological samples of feces, saliva, sewage, and sputum were performed. Mono- and co-cultures were used to identify volatile production from individual bacterial species or in combination with stable isotope probing to identify the active metabolism of microbes from the biological samples.
Vacuum-assisted sorbent extraction (VASE) was employed to extract the VOCs. VASE is an easy-to-use, commercialized, solvent-free headspace extraction method for semi-volatile and volatile compounds. The lack of solvents and the near-vacuum conditions used during extraction make developing a method relatively easy and fast when compared to other extraction options such as tert-butylation and solid phase microextraction. The workflow described here was used to identify specific volatile signatures from mono- and co-cultures. Furthermore, analysis of the stable isotope probing of human associated biological samples identified VOCs that were either commonly or uniquely produced. This paper presents the general workflow and experimental considerations of VASE in conjunction with stable isotope probing of live microbial cultures.

This protocol describes the extraction of volatile organic compounds from a biological sample with the vacuum-assisted sorbent extraction method, gas chromatography coupled with mass spectrometry using the Entech Sample Preparation Rail, and data analysis. It also describes culture of biological samples and stable isotope probing.

通过真空辅助吸附剂提取从人类相关样品中捕获活性产生的微生物挥发性有机化合物

Volatile organic compounds (VOCs) from biological samples have unknown origins. VOCs may originate from the host or different organisms from within the ...

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.