财政支持由国土安全科学部和技术局提供。

1，仪器准备<ol><li>确保仪器，烤箱，和探测器都是在室温。关闭气流入口和检测器。 </li><li>从GC上取下的TDS。查阅制造商的用户手册，仪器专用程序。 </li><li>从独联体进口取出TDS适配器和独联体取出内胆。 </li><li>检查独联体国家进口的颗粒和碎片，而衬垫被删除。清洁任何可见的碎片用压缩空气，或优选氮气。 </li><li>附加一个新的石墨密封垫圈使用的套圈对班轮结合由制造商提供工具和说明新的独联体衬垫。 </li><li>将眼线用附带的石墨密封垫圈进入独联体。更换TDS适配器并重新安装TDS。 </li><li>从包装中取出新的列和删除列两端的硅胶保护。 </li><li>将螺母和密封垫圈柱的两端。使用ECD检测器螺母和ferrule表示该列的一端和一个CIS套箍柱的另一端。 </li><li>使用陶瓷柱切削工具中，从柱的每个端部除去约10厘米。确保螺母和卡套留在列，但离柱的末端，以避免堵塞和碎片。 </li><li>固定列到使用仪器制造商的指引烤箱。将色谱柱插入进样口。连接柱与检测器端口的另一端。插入的深度是特定仪器，进样口和检测器的制造商。请参见用户手册和规范的确切列的插入深度。 注意:预烘烤可能需要的列的列的相对端连接到检测器端口之前。咨询柱和仪器制造商的文档，以确定是否需要进行预烘烤。 </li><li>轻轻用手拧紧螺母和卡套到各自的端​​口入口和检测器。用扳手拧紧无线TH约旋转四分之一圈的螺母和卡套。用力过猛或过度紧缩将破坏导致泄漏套圈或列来打破和堵塞。 </li><li>烤出来的TDS，进气口，色谱柱和检测。一个典型的烘烤出包括设置温度为所有区域的正下方的最高工作温度（通常为300℃），而流动的载气，至少2小时。 </li><li>酷所有区域并拧紧所有螺母和卡套，以确保无泄漏操作。烘烤出在加热和冷却将导致螺母和密封垫圈松动，这可以引入泄漏。 </li><li>加载，或者使用软件界面刷新，仪器方法。验证正确的温度和流量已经实现。仪器已准备好进行分析。 </li></ol> 2，准备标准<ol><li>从拆下1,000纳克微升-1 3,4-DNT，10,000纳克微升-1 TNT，和10,000纳克微升-1 RDX冷冻或冷藏库，并允许3储备溶液达到室温。 </li><li>免除100微升的股票1,000毫微微升-1 3,4-DNT和添加900μL乙腈为琥珀色样品瓶。 </li><li>免除100微升100纳克微升-1来自步骤2.2 3,4 -二硝基甲苯溶液，并加入900微升乙腈中的成琥珀色样品瓶。 </li><li>免除150微升的10毫微微升-1从步骤2.3和4,850微升乙腈3,4 -二硝基甲苯溶液放入一个琥珀色样品瓶。这是用于直接液体沉积的内部标准。 </li><li>分配100μl的库存10,000纳克微升-1 TNT溶液，加入100μl的库存10,000纳克微升-1 RDX溶液和800微升乙腈中成琥珀色样品瓶。 </li><li>分配100μl的1,000纳克微升-1 TNT和步骤2.5及900微升的乙腈溶液RDX成琥珀色样品瓶。 </li><li>分配100μl的在100毫微微升-1 TNT和RDX来自步骤2.6和900微升的乙腈溶液为琥珀色样品瓶。 </li><li>免除100微升为10 ngμL-1 TNT和从步骤2.7和900μL乙腈RDX解决方案为琥珀色样品瓶。这将创建1.0 TNT/1.0 RDX纳克微升-1解决方案的标准准备直接液体沉积到样品管。 </li><li>免除60微升为10 ngμL-1的解决方案在第2.7步和940μL乙腈为琥珀色样品瓶。这将创建0.6 TNT/0.6 RDX纳克微升-1解决方案的标准准备直接液体沉积到样品管。 </li><li>免除40微升为10 ngμL-1的解决方案在第2.7步和960μL乙腈为琥珀色样品瓶。这将创建0.4 TNT/0.4 RDX纳克微升-1解决方案的标准准备直接液体沉积到样品管。 </li><li>免除20微升10纳克μL-1的溶液在步骤2.7和980微升乙腈中成琥珀色样品瓶。这将创建0.2 TNT/0.2 RDX纳克微升-1解决方案的标准准备直接液体沉积到样品管。 </li><li>分配100μl的1.0毫微微升-1在步骤2.8和900微升的乙腈溶液为琥珀色样品瓶。这将创建0.1 TNT/0.1 RDX纳克微升-1解决方案的标准准备直接液体沉积到样品管。 </li></ol> 3，样品采集<ol><li>连接一个吸附剂填充的热脱附样品管使用一小片的弹性硅胶管的样品泵或类似设备。设置在指示空气的流动方向为样品吸附的样品管的红色箭头，但应指出的硅橡胶管和样品泵的方向。 </li><li>连接的活塞流量计的样品管在从样品PUM的相对端p附着在步骤3.1。调节流速上样泵或类似设备，以使得流量约为100毫升·分-1通过样品管，根据从活塞流量计的读数。流率应设置为±5.0毫升·分100毫升·分-1所需的设定点的-1。 </li><li>从样品管断开活塞流量计及暂时关闭采样泵，但留下连接到泵的样品管中。样品泵将被重新激活，开始收集样本。样品管可以领取。 </li><li>将样品管中的炸药蒸汽流的仍然连接采样泵。蒸汽源可以是固体样品上面的空间，一个开放的环境，还是各种分析物汽化系统。 </li><li>设置基于表2中列出的近似的取样时间的计时器。采样时间被列为基础上suspec一般指引材料在气相泰德浓度。这些采样时间，用100毫升·分-1的流速，一般会产生大量的校准曲线，这是理想的定量的中心。 </li><li>激活的样品泵和启动定时器。等到计时器停止和关闭采样泵关闭。从泵断开样品管，并将其放置在设置有该样品管的包装中。盖上管和商店进行分析。 </li><li>记录标记到每个样品管，样品的时间，流速为在实验室笔记本的样品管中的唯一的序列号。这些值将被用于定量重要。 </li></ol> 4，校准曲线生成<ol><li>吸管5.0微升直接在一个未使用的，空调的样品管中的玻璃料的溶液的标准。保持样品管和移液管直立用戴着手套的手在沉积过程中。 </li><li>重复步骤4.1各六个月CALIBRATIO的Ñ​​标准到三个不同的样品管。 </li><li>存款5微升的0.3毫微微升-1在各管3,4-DNT为好。 </li><li>让18的样品管（3每个溶液的浓度，6溶液浓度）坐于室温至少30分钟，使溶剂蒸发。 </li><li>使用20管自动进样器和前面描述的TNT和RDX TDS-CIS-GC-ECD方法来运行和分析所有18管的O / N。24,25的TDS-CIS-GC-ECD参数方法的概要在表1中提供。 </li><li>整合与3,4 - 二硝基甲苯，TNT，RDX和色谱图中的每个18采样管的相关联的峰值。 3,4-DNT，TNT和RDX的峰值将出现在约4.16，4.49和4.95分，分别。 </li><li>注意3,4-DNT，TNT和RDX各18管沿与TNT和RDX的相应的质量沉积在样品管中电子表格和LABORATOR该峰面积Y笔记本。 </li><li>由峰面积为3,4 - 二硝基甲苯将每个峰面积归一化均TNT和RDX的峰面积。这样做对所有18管。 </li><li>计算归一化的TNT和RDX峰面积为6标准浓度的平均值和标准偏差。 </li><li>画出平均标准化峰面积与分析物的质量上存在的管为TNT和RDX。 </li><li>添加一个线性趋势线同时为TNT和RDX的数据点。确定的斜率和y轴截距为每种分析物。记录斜率，截距，并在电子表格和实验室笔记本R2值。 </li><li>用于放置样品管中管机3小时，在300ºC和500毫升分钟-1氮气流。 </li></ol> 5，样品分析<ol><li>存款5.0微升的0.3纳克微升-1对每个样品管的3,4-DNT。 </li><li>允许管坐于室温至少30分钟，以从在蒸发溶剂TERNAL标准。 </li><li>使用20管自动进样器和前面描述的TNT和RDX的方法来对TDS-CIS-GC-ECD。24,25运行管O / N仪表参数分析方法的汇总，如表1。 </li><li>整合与3,4 - 二硝基甲苯，TNT，RDX和色谱图中的每个18采样管的相关联的峰值。 3,4-DNT，TNT和RDX的峰值将出现在约4.16，4.49和4.95分，分别。 </li><li>注意3,4-DNT，TNT和RDX峰面积为每一个电子表格和实验室笔记本的样品管。 </li><li>用峰面积和校正曲线来计算蒸气浓度分之十亿体积（PPB v）每分析。见方程1-4。 </li><li>用于放置样品管中管机3小时，在300ºC和500毫升分钟-1氮气气流。 </li></ol>

<ol>
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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+Peak+Detection+and+Matching+Algorithm+for+Gas+Chromatography&#8722;Differential+Mobility+Spectrometry.">Automated Peak Detection and Matching Algorithm for Gas Chromatography&#8722;Differential Mobility Spectrometry.</a> Analytical Chemistry. 83 (5), 1537-1546 (2011).</li><li>Hargrove, W. F., Rosenthal, D., Cooley, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+algorithm+for+peak+detection+in+automatic+gas+chromatography-mass+spectrometry+data+processing.">Improvement of algorithm for peak detection in automatic gas chromatography-mass spectrometry data processing.</a> Analytical Chemistry. 53 (3), 538-539 (1981).</li><li>Middleditch, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Analytical Artifacts GC, MS, HPLC, TLC and PC. 44, (1989).</li></ol>

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再现性对于使用直接液相沉积法与TDS-CIS-GC-ECD仪器仪表，相对标准偏差（RSD）跟踪易燃易爆气体的定量分析的一个关键属性是经常被用来作为衡量标准的重现性。我们经历了相对标准偏差之间和内部样本的TNT炸药约5％，而RDX 10％的重现性。 15％以上的任何RSD作为一个指标来检查变化，以减少该协议的有效性常见的来源。变异来源已导致不可接受的相对标准偏差在过去在下面的讨论中被突出显示。 ...

气相色谱法（GC）是分析化学的核心仪器分析技术，可以说是一样普及，因为在一个化学实验室电热板或平衡。气相色谱仪，可用于制备，鉴定和定量多种化学化合物的组成，可被耦合到各种探测器，如火焰离子化检测器（FID的），光离子化检测器（PID），热导检测器（的TCD的），电子捕获检测器（ECD的），和质谱仪（MS），根据不同的被分析物，方法和应用。样品可以通过一个标准的分流/不分流进样口与小样本的解决方案，专业的顶空分析入口，固相微萃取（SPME）注射器，或热脱附系统时推出。 GC-MS往往是在可替代的或新出现，检测技术，因为它的效用，柔韧性的确认和验证的应用程序中使用的标准技术，与既定的化学数据库和图书馆1识别电源- 7 GC和其相关的采样和检测元件是理想的常规化学分析和更专业的，具有挑战性的分析应用。 越来越多的关注军事，国土安全，和商业企业的分析应用是跟踪爆炸性气体的检测，以检测包括定性和定量。爆炸物痕量气体探测是一种独特的分析化学的挑战，因为分析物，如2,4,6 - 三硝基甲苯（TNT）和环三亚甲基三（RDX）的物理性质，使它们特别难以处理和单独使用更广泛的，更通用的化学分析方法。相对较低的蒸气压和分份每百万体积（ppm的V）饱和蒸气浓度，结合相对高粘着系数，necessit吃了专项抽检协议，仪器仪表，定量方法8 - 12耦合到电子捕获检测器（ECD）或质谱仪（MS）在气相色谱是一种有效的方法，定量分析物爆炸，特别是二硝基甲苯（DNT），TNT和RDX ，6,13 -因为其相对较高的电子亲和力的17 GC-ECD为硝基能量化合物特别有用。美国环境保护署（EPA）已建立的标准方法对炸药分析物检测用GC-ECD和GC-MS，但这些方法都集中于在溶液中的样品，如地下水，并收集在蒸汽相中没有样品。2 ，18 - 23为了检测爆炸性蒸气，替代取样协议必须被使用，如蒸汽收集用吸附剂填充的热脱附样品管，但定量地检测，由于缺乏标准的蒸气仍难以一ND校准方法，不占样品管和仪表的损失。 最近，采用热脱附系统与冷却入口系统（TDS-CIS），耦合到GC-ECD定量方法已经被开发用于TNT和RDX蒸气。24,25与TDS-CIS-GC-ECD仪器相关联的损失痕量爆炸物蒸气进行了表征，并计入例如校准曲线采用直接液相沉积法到吸附剂填充热脱附样品管。然而，文献集中在表征仪器和方法的发展，但实际上从未采样，分析，定量或爆炸性蒸气，唯一的解决方案的标准。这里，重点是协议取样和定量爆炸性蒸气。协议和方法可扩展到其它分析物和痕量爆炸物蒸气，如季戊四醇四硝酸酯（PETN）。

<table><tbody><tr><td>2,4,6-Trinitrotoluene (TNT)</td><td>Accu-Standard</td><td>M-8330-11-A-10X</td><td>10,000 ng &amp;mu;l&lt;sup&gt;-1&lt;/sup&gt;</td></tr><tr><td>Cyclotrimethylenetrinitramine (RDX)</td><td>Accu-Standard</td><td>M-8330-05-A-10X</td><td>10,000 ng &amp;mu;l&lt;sup&gt;-1&lt;/sup&gt;</td></tr><tr><td>3,4-Dinitrotoluene (3,4-DNT)</td><td>Accu-Standard</td><td>S-22988-01</td><td>1,000 ng &amp;mu;l&lt;sup&gt;-1&lt;/sup&gt;</td></tr><tr><td>Tenax&amp;reg; TA Vapor Sample Tubes</td><td>Gerstel</td><td>009947-000-00</td><td>Tenax&amp;reg; 60/80</td></tr><tr><td>CIS4 Liner</td><td>Gerstel</td><td>014652-005-00</td><td>or equivalent</td></tr><tr><td>Transfer Line Ferrule</td><td>Gerstel</td><td>001805-008-00</td><td></td></tr><tr><td>Inlet Liner Ferrule</td><td>Gerstel</td><td>001805-040-00</td><td></td></tr><tr><td>CIS4 Ferrule</td><td>Gerstel</td><td>007541-010-00</td><td></td></tr><tr><td>ECD Detector Ferrule</td><td>Agilent</td><td>5181-3323</td><td></td></tr><tr><td>DB5-MS Column</td><td>Res-Tek</td><td>12620</td><td></td></tr></tbody></table>

quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector

的解决方案标准的直接液体沉积到吸附剂填充的热脱附管用于跟踪爆炸性气体样品的定量分析。直接液体沉积方法产生蒸气样品的分析和解决方案的标准分析之间具有更高的保真度比使用单独的注射方法，蒸汽和溶液， 即 ，收集在小瓶中的溶液制备的蒸气收 ​​集管和标准样品。此外，该方法可占仪器仪表的损失，这使得它非常适合最大限度地减少可变性和定量的微量化学检测。气相色谱电子捕获检测器是一个仪表配置硝基能源，如TNT和RDX，由于其相对高的电子亲和势敏感。然而，这些化合物的蒸气定量是困难而不可行的蒸气的标准。因此，我们消除蒸气标准的要求，结合使用直接液体沉积协议分析跟踪爆炸性蒸气样品的仪器的灵敏度。

获得定量结果跟踪爆炸性气体样品开始建立的校准曲线使用的解决方案标准的直接液相沉积法到样品管占亏损仪器和解决方案的标准和蒸气样品之间的差异的TDS-CIS-GC-ECD检测仪器。在TDS-CIS-GC-ECD的仪器和方法，用于TNT和RDX微量分析进行了详细的先前描述的其他地方，但仪器参数列于表1中 。24,25在这里， 图1显示了使用一系列色谱图中得到的发表于表1的...

Watch this Scientific Journal Video about Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector at JoVE.com

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

微量TNT和RDX的收集吸附剂填充热脱附管爆炸蒸汽是用连接到GC用电子捕获检测器程序升温脱附系统进行分析。仪器分析是结合直接液相沉积法，以减少样品变性和账户仪器漂移和损失。

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 ...

quantitative-detection-trace-explosive-vapors-programmed-temperature

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

19.6K 次观看.  U.S. Naval Research Laboratory. 微量TNT和RDX的收集吸附剂填充热脱附管爆炸蒸汽是用连接到GC用电子捕获检测器程序升温脱附系统进行分析。仪器分析是结合直接液相沉积法，以减少样品变性和账户仪器漂移和损失。 

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

Light-driven Enzymatic Decarboxylation

Oxidoreductases belong to the most-applied industrial enzymes. Nevertheless, they need external electrons whose supply is often costly and challenging. Recycling of the electron donors NADH or NADPH requires the use of additional enzymes and sacrificial substrates. Interestingly, several oxidoreductases accept hydrogen peroxide as electron donor. While being inexpensive, this reagent often reduces the stability of enzymes. A solution to this problem is the in situ generation of the cofactor. The continuous supply of the cofactor at low concentration drives the reaction without impairing enzyme stability. This paper demonstrates a method for the light-catalyzed in situ generation of hydrogen peroxide with the example of the heme-dependent fatty acid decarboxylase OleTJE. The fatty acid decarboxylase OleTJE was discovered due to its unique ability to produce long-chain 1-alkenes from fatty acids, a hitherto unknown enzymatic reaction. 1-alkenes are widely used additives for plasticizers and lubricants. OleTJE has been shown to accept electrons from hydrogen peroxide for the oxidative decarboxylation. While addition of hydrogen peroxide damages the enzyme and results in low yields, in situ generation of the cofactor circumvents this problem. The photobiocatalytic system shows clear advantages regarding enzyme activity and yield, resulting in a simple and efficient system for fatty acid decarboxylation.

We describe a protocol for the light-catalyzed generation of hydrogen peroxide &#8212; a cofactor for oxidative transformations.

光驱动脱羧酶

Oxidoreductases belong to the most-applied industrial enzymes. Nevertheless, they need external electrons whose supply is often costly and challenging. ...

科研

化学

Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important step to conservation of flowers that are threatened or endangered. Because floral fragrance is critical for attracting pollinators, this method could be used to better understand or even enhance pollination. We present a protocol using a portable charcoal air filter and vacuum to collect floral fragrance volatiles, which are then analyzed by a GC-MS. By using this method, fragrance volatiles can be sampled using a non-destructive method with a machine that is easily transported. This methodology uses a rapid sampling procedure, cutting sampling time down from 2-3 hours to approximately 10 minutes. Using GC-MS, the fragrance compounds can be identified individually, based on authentic standards. The steps used for collecting fragrance and control data are presented, from material setup to collecting the data output.

Here, we present a protocol for collecting the floral fragrance volatiles from blooming flowers, using a non-destructive sampling procedure.

使用头空间挥发性收集技术快速收集花香挥发物，用于 GC-MS 热解吸采样

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important ...

生物化学

Quantitative Analysis by Thermogravimetry-Mass Spectrum Analysis for Reactions with Evolved Gases

During energy conversion, material production, and metallurgy processes, reactions often have the features of unsteadiness, multistep, and multi-intermediates. Thermogravimetry-mass spectrum (TG-MS) is seen as a powerful tool to study reaction features. However, reaction details and reaction mechanics have not been effectively obtained directly from the ion current of TG-MS. Here, we provide a method of an equivalent characteristic spectrum analysis (ECSA) for analyzing the mass spectrum and giving the mass flow rate of reaction gases as precise as possible. The ECSA can effectively separate overlapping ion peaks and then eliminate the mass discrimination and temperature-dependent effect. Two example experiments are presented: (1) the decomposition of CaCO3 with evolved gas of CO2 and the decomposition of hydromagnesite with evolved gas of CO2 and H2O, to evaluate the ECSA on single-component system measurement and (2) the thermal pyrolysis of Zhundong coal with evolved gases of inorganic gases CO, H2, and CO2, and organic gases C2H4, C2H6, C3H8, C6H14, etc., to evaluate the ECSA on multi-component system measurement. Based on the successful calibration of the characteristic spectrum and relative sensitivity of specific gas and the ECSA on mass spectrum, we demonstrate that the ECSA accurately gives the mass flow rates of each evolved gas, including organic or inorganic gases, for not only single but multi-component reactions, which cannot be implemented by the traditional measurements.

Precise determination of the evolved gases&#39; flow rate is key to study the details of reactions. We provide a novel quantitative analysis method of equivalent characteristic spectrum analysis for thermogravimetry-mass spectrum analysis by establishing the calibration system of the characteristic spectrum and relative sensitivity, for obtaining the flow rate.

热重分析-质谱分析对演化气体反应的定量分析

During energy conversion, material production, and metallurgy processes, reactions often have the features of unsteadiness, multistep, and ...

工程学

A Two-Step Pyrolysis-Gas Chromatography Method with Mass Spectrometric Detection for Identification of Tattoo Ink Ingredients and Counterfeit Products

Tattoo inks are complex mixtures of ingredients. Each of them possesses different chemical properties which have to be addressed upon chemical analysis. In this method for two-step pyrolysis online coupled to gas chromatography mass spectrometry (py-GC-MS) volatile compounds are analyzed during a first desorption run. In the second run, the same dried sample is pyrolyzed for analysis of non-volatile compounds such as pigments and polymers. These can be identified by their specific decomposition patterns. Additionally, this method can be used to differentiate original from counterfeit inks. Easy screening methods for data evaluation using the average mass spectra and self-made pyrolysis libraries are applied to speed up substance identification. Using specialized evaluation software for pyrolysis GS-MS data, a fast and reliable comparison of the full chromatogram can be achieved. Since GC-MS is used as separation technique, the method is limited to volatile substances upon desorption and after pyrolysis of the sample. The method can be applied for quick substance screening in market control surveys since it requires no sample preparation steps.

This method for two-step pyrolysis online coupled to gas chromatography with mass spectrometric detection and data evaluation protocol can be used for multi-component analysis of tattoo inks and discrimination of counterfeit products.

一种用于检测纹身油墨成分和假冒产品的两步热解-气相色谱法

Tattoo inks are complex mixtures of ingredients. Each of them possesses different chemical properties which have to be addressed upon chemical analysis. ...

Qualitative Characterization of the Aqueous Fraction from Hydrothermal Liquefaction of Algae Using 2D Gas Chromatography with Time-of-flight Mass Spectrometry

Two-dimensional gas chromatography coupled with time-of-flight mass spectrometry is a powerful tool for identifying and quantifying chemical components in complex mixtures. It is often used to analyze gasoline, jet fuel, diesel, bio-diesel and the organic fraction of bio-crude/bio-oil. In most of those analyses, the first dimension of separation is non-polar, followed by a polar separation. The aqueous fractions of bio-crude and other aqueous samples from biofuels production have been examined with similar column combinations. However, sample preparation techniques such as derivatization, solvent extraction, and solid-phase extraction were necessary prior to analysis. In this study, aqueous fractions obtained from the hydrothermal liquefaction of algae were characterized by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry without prior sample preparation techniques using a polar separation in the first dimension followed by a non-polar separation in the second. Two-dimensional plots from this analysis were compared with those obtained from the more traditional column configuration. Results from qualitative characterization of the aqueous fractions of algal bio-crude are discussed in detail. The advantages of using a polar separation followed by a non-polar separation for characterization of organics in aqueous samples by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry are highlighted.

A two-dimensional gas chromatography-time-of-flight mass spectrometry method is described for characterization of the aqueous fraction of bio-crude produced from hydrothermal liquefaction of algae. This protocol can also be employed to analyze the aqueous fraction of liquid products from fast pyrolysis, catalytic fast pyrolysis, catalytic deoxygenation and hydro-treating.

从藻类水热液化使用二维气相色谱时间飞行质谱法水提取部分的定性鉴定

Two-dimensional gas chromatography coupled with time-of-flight mass spectrometry is a powerful tool for identifying and quantifying chemical components in ...

生物工程

Chromatographic Fingerprinting by Template Matching for Data Collected by Comprehensive Two-Dimensional Gas Chromatography

Data processing and evaluation are critical steps of comprehensive two-dimensional gas chromatography (GCxGC), particularly when coupled to mass spectrometry. The rich information encrypted in the data may be highly valuable but difficult to access efficiently. Data density and complexity can lead to long elaboration times and require laborious, analyst-dependent procedures. Effective yet accessible data processing tools, therefore, are key to enabling the spread and acceptance of this advanced multidimensional technique in laboratories for daily use. The data analysis protocol presented in this work uses chromatographic fingerprinting and template matching to achieve the goal of highly automated deconstruction of complex two-dimensional chromatograms into individual chemical features for advanced recognition of informative patterns within individual chromatograms and across sets of chromatograms. The protocol delivers high consistency and reliability with little intervention. At the same time, analyst supervision is possible in a variety of settings and constraint functions that can be customized to provide flexibility and capacity to adapt to different needs and goals. Template matching is shown here to be a powerful approach to explore extra-virgin olive oil volatilome. Cross-alignment of peaks is performed not only for known targets, but also for untargeted compounds, which significantly increases the characterization power for a wide range of applications. Examples are presented to evidence the performance for the classification and comparison of chromatographic patterns from sample sets analyzed under similar conditions.

This protocol presents an approach to fingerprint and explore multi-dimensional data collected by comprehensive two-dimensional gas chromatography coupled to mass spectrometry. Dedicated pattern recognition algorithms (template matching) are applied to explore the chemical information encrypted in the extra-virgin olive oil volatile fraction (i.e., volatilome).

通过模板匹配对综合二维气相色谱收集的数据进行色谱指纹

Data processing and evaluation are critical steps of comprehensive two-dimensional gas chromatography (GCxGC), particularly when coupled to mass ...

Gas Chromatography-Mass Spectrometry Paired with Total Vaporization Solid-Phase Microextraction as a Forensic Tool

Gas Chromatography &#8211; Mass Spectrometry (GC-MS) is a frequently used technique for the analysis of numerous analytes of forensic interest, including controlled substances, ignitable liquids, and explosives. GC-MS can be coupled with Solid-Phase Microextraction (SPME), in which a fiber with a sorptive coating is placed into the headspace above a sample or immersed in a liquid sample. Analytes are sorbed onto the fiber which is then placed inside the heated GC inlet for desorption. Total Vaporization Solid-Phase Microextraction (TV-SPME) utilizes the same technique as immersion SPME but immerses the fiber into a completely vaporized sample extract. This complete vaporization results in a partition between only the vapor phase and the SPME fiber without interference from a liquid phase or any insoluble materials. Depending upon the boiling point of the solvent used, TV-SPME allows for large sample volumes (e.g., up to hundreds of microliters). On-fiber derivatization may also be performed using TV-SPME. TV-SPME has been used to analyze drugs and their metabolites in hair, urine, and saliva. This simple technique has also been applied to street drugs, lipids, fuel samples, post-blast explosive residues, and pollutants in water. This paper highlights the use of TV-SPME to identify illegal adulterants in very small samples (microliter quantities) of alcoholic beverages. Both gamma-hydroxybutyrate (GHB) and gamma-butyrolactone (GBL) were identified at levels that would be found in spiked drinks. Derivatization by a trimethylsilyl agent allowed for conversion of the aqueous matrix and GHB into their TMS derivatives. Overall, TV-SPME is quick, easy, and requires no sample preparation aside from placing the sample into a headspace vial.

Total Vaporization Solid Phase Microextraction (TV-SPME) completely vaporizes a liquid sample whilst analytes are sorbed onto a SPME fiber. This allows for partitioning of the analyte between only the solvent vapor and the SPME fiber coating.

气相色谱-质量光谱学与总蒸发固体相微切成一对，作为取证工具

Gas Chromatography &#8211; Mass Spectrometry (GC-MS) is a frequently used technique for the analysis of numerous analytes of forensic interest, including ...

Gas Chromatography (GC) with Flame-Ionization Detection

Source: Laboratory of Dr. B. Jill Venton - University of Virginia
Gas chromatography (GC) is used to separate and detect small molecular weight compounds in the gas phase. The sample is either a gas or a liquid that is vaporized in the injection port. Typically, the compounds analyzed are less than 1,000 Da, because it is difficult to vaporize larger compounds. GC is popular for environmental monitoring and industrial applications because it is very reliable and can be run nearly continuously. GC is typically used in applications where small, volatile molecules are detected and with non-aqueous solutions. Liquid chromatography is more popular for measurements in aqueous samples and can be used to study larger molecules, because the molecules do not need to vaporize. GC is favored for nonpolar molecules while LC is more common for separating polar analytes.
The mobile phase for gas chromatography is a carrier gas, typically helium because of its&#160;low molecular weight and being chemically inert. Pressure is applied and the mobile phase moves the analyte through the column. The separation is accomplished using a column coated with a stationary phase. Open tubular capillary columns are the most popular columns and have the stationary phase coated on the walls of the capillary. Stationary phases are often derivatives of polydimethylsiloxane, with 5&#8211;10% of the groups functionalized to tune the separation. Typical functional groups are phenyl, cyanopropyl, or trifluoropropyl groups. Capillary columns are usually 5&#8211;50 m&#160;long. Narrower columns have higher resolution but require higher pressures. Packed columns can also be used where the stationary phase is coated onto beads packed in the column. Packed columns are shorter, 1&#8211;5 m. Open tubular capillaries are generally preferred because they allow higher efficiencies, faster analyses, and have higher capacities.
Flame-ionization detection (FID) is a good general detector for organic compounds in GC that detects the amount of carbon in a sample. After the column, samples are burned in a hot, hydrogen-air flame. Carbon ions are produced by the combustion. While the overall efficiency of the process is low (only 1 in 105 carbon ions produce an ion in the flame) the total amount of ions is directly proportional to the amount of carbon in the sample. Electrodes are used to measure the current from the ions. FID is a destructive detector, as the entire sample is pyrolyzed. FID is unaffected by noncombustible gases and water.

Gas Chromatography GC with Flame-Ionization Detection

气相色谱 (GC) 与火焰电离检测

Source: Laboratory of Dr. B. Jill Venton - University of Virginia
Gas chromatography (GC) is used to separate and detect small molecular weight compounds ...

教育

JoVE Science Education

分析化学

Gas Chromatography: Overview of Detectors

Detectors in gas chromatography (GC) help identify and quantify the components of a mixture by translating chemical properties into measurable signals, which are displayed on a chromatogram. Detectors can be categorized into two main types: destructive and non-destructive.
A non-destructive detector allows a sample to be analyzed without altering or consuming it, meaning the sample can be collected after detection for further analysis. Examples include thermal conductivity detectors and electron capture detectors.
On the other hand, a destructive detector causes chemical changes in the analyte or completely consumes it during detection, making it impossible to recover the sample afterward. This often involves burning or chemically reacting the sample, making recovery impossible. Examples include flame ionization and nitrogen-phosphorus detectors, which combust the sample.
An ideal gas chromatography detector should be non-destructive and possess high sensitivity for detecting low analyte concentrations. It should exhibit responsiveness to all analytes or selectively respond to specific classes of analytes while maintaining a linear response across a wide concentration range. Linearity indicates that the detector&#39;s response is directly proportional to the concentration of the analytes, making it easier to quantify the amount present. Stability, reliability, and reproducibility are crucial, with the detector being insensitive to variations in flow rate and temperature. Achieving a short response time, independent of flow rate, enhances the sample throughput and reduces analysis time for large sample quantities. Furthermore, the detector should exhibit minimal interference from sample matrix components and compatibility with various analyte types. Lastly, robustness and durability are vital characteristics, ensuring the detector&#39;s reliability and resilience under the conditions encountered in gas chromatography analysis.
Gas chromatography analysis commonly utilizes thermal conductivity, flame ionization, mass spectrometer, thermionic, electrolytic conductivity, photoionization, FTIR, and electron capture detectors.
Flame ionization detectors offer a broader linear response range, albeit destroying the sample, and possess a higher detection limit compared to thermal conductivity detectors. Electron capture detectors exhibit excellent detection limits but have a relatively narrow linear range. Ultimately, the choice of the detector depends on the type of the sample under analysis and the detector&#39;s typical detection limit.

气相色谱法:检测器概述

Detectors in gas chromatography (GC) help identify and quantify the components of a mixture by translating chemical properties into measurable signals, ...

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

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光驱动脱羧酶

使用头空间挥发性收集技术快速收集花香挥发物，用于 GC-MS 热解吸采样

热重分析-质谱分析对演化气体反应的定量分析

一种用于检测纹身油墨成分和假冒产品的两步热解-气相色谱法

从藻类水热液化使用二维气相色谱时间飞行质谱法水提取部分的定性鉴定

通过模板匹配对综合二维气相色谱收集的数据进行色谱指纹

气相色谱-质量光谱学与总蒸发固体相微切成一对，作为取证工具

气相色谱 (GC) 与火焰电离检测

气相色谱法:检测器概述

气相色谱法:检测器概述