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>

We have nothing to disclose.

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 border="0" cellpadding="0" cellspacing="0" width="638">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:127px;">Company</td>
			<td style="width:128px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">2,4,6-Trinitrotoluene (TNT)</td>
			<td style="width:127px;">Accu-Standard</td>
			<td style="width:128px;">M-8330-11-A-10X</td>
			<td>10,000 ng &#956;L-1</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Cyclotrimethylenetrinitramine (RDX)</td>
			<td style="width:127px;">Accu-Standard</td>
			<td style="width:128px;">M-8330-05-A-10X</td>
			<td>10,000 ng &#956;L-1</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">3,4-Dinitrotoluene (3,4-DNT)</td>
			<td style="width:127px;">Accu-Standard</td>
			<td style="width:128px;">S-22988-01</td>
			<td>1000 ng &#956;L-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tenax&#174; TA Vapor Sample Tubes</td>
			<td style="width:127px;">Gerstel</td>
			<td style="width:128px;">009947-000-00</td>
			<td>Tenax&#174; 60/80</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CIS4 Liner</td>
			<td style="width:127px;">Gerstel</td>
			<td style="width:128px;">014652-005-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Transfer Line Ferrule</td>
			<td style="width:127px;">Gerstel</td>
			<td style="width:128px;">001805-008-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Inlet Liner Ferrule</td>
			<td style="width:127px;">Gerstel</td>
			<td style="width:128px;">001805-040-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CIS4 Ferrule</td>
			<td style="width:127px;">Gerstel</td>
			<td style="width:128px;">007541-010-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ECD Detector Ferrule</td>
			<td style="width:127px;">Aglient</td>
			<td style="width:128px;">5181-3323</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DB5-MS Column</td>
			<td style="width:127px;">Res-Tek</td>
			<td style="width:128px;">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

Research

JoVE Journal

Chemistry

19.5K 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

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date back to the early 1980s the focus of these early papers primarily characterized the changes to the structures under extremely harsh conditions (pH or temperature)1-3. It is also known that paramagnetic molecular oxygen undergoes a Heisenberg spin exchange interaction with stable radicals that extremely broadens the EPR signal4-6. Recently, we reported interesting results where this interaction of molecular oxygen with a certain part of the existing stable radical structure can be reversibly affected simply by flowing a diamagnetic gas through the carbon samples at STP7. As flows of He, CO2, and N2 had a similar effect these interactions occur at the surface area of the macropore system.
This manuscript highlights the experimental techniques, work-up, and analysis towards affecting the existing stable radical nature in the carbon structures. It is hoped that it will help towards further development and understanding of these interactions in the community at large.

Stable radicals that are present in carbon substrates interact with paramagnetic oxygen through a Heisenberg spin exchange. This interaction can be significantly reduced under STP conditions by flowing a diamagnetic gas over the carbon system. This manuscript describes a simple method to characterize the nature of those radicals.

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

科研

化学

Facile Preparation of 4-Substituted Quinazoline Derivatives

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted 2-aminobenzophenones and thiourea in the presence of dimethyl sulfoxide (DMSO). This is a unique complementary reaction system in which thiourea undergoes thermal decomposition to form carbodiimide and hydrogen sulfide, where the former reacts with 2-aminobenzophenone to form 4-phenylquinazolin-2(1H)-imine intermediate, whilst hydrogen sulfide reacts with DMSO to give methanethiol or other sulfur-containing molecule which then functions as a complementary reducing agent to reduce 4-phenylquinazolin-2(1H)-imine intermediate into 4-phenyl-1,2-dihydroquinazolin-2-amine. Subsequently, the elimination of ammonia from 4-phenyl-1,2-dihydroquinazolin-2-amine affords substituted quinazoline derivative. This reaction usually gives quinazoline derivative as a single product arising from 2-aminobenzophenone as monitored by GC/MS analysis, along with small amount of sulfur-containing molecules such as dimethyl disulfide, dimethyl trisulfide, etc. The reaction usually completes in 4-6 hr at 160 &#186;C in small scale but may last over 24 hr when carried out in large scale. The reaction product can be easily purified by means of washing off DMSO with water followed by column chromatography or thin layer chromatography.

A protocol for facile preparation of 4-substituted quinazoline derivatives from 2-aminobenzophenones, thiourea and dimethyl sulfoxide is presented.

的4-取代喹唑啉衍生物简便制备

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted ...

Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system includes a reactor, furnace, gas and vapor sources, flow control, instrumentation to quantify reaction products (e.g., gas chromatograph), and instrumentation to monitor the reaction in real time (e.g., mass spectrometer). Here, we apply the TPRxn methodology to study molybdenum carbide catalysts for the deoxygenation of acetic acid, an important reaction among many in the upgrading/stabilization of biomass pyrolysis vapors. TPRxn is used to evaluate catalyst activity and selectivity and to test hypothetical reaction pathways (e.g., decarbonylation, ketonization, and hydrogenation). The results of the TPRxn study of acetic acid deoxygenation show that molybdenum carbide is an active catalyst for this reaction at temperatures above ca. 300 &#176;C and that the reaction favors deoxygenation (i.e., C-O bond-breaking) products at temperatures below ca. 400 &#176;C and decarbonylation (i.e., C-C bond-breaking) products at temperatures above ca. 400 &#176;C.

Presented here is a protocol for the operation of a micro-scale temperature-programmed reactor for evaluating the catalytic performance of molybdenum carbide during acetic acid deoxygenation.

对碳化钼催化合成乙酸的程序升温脱氧

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system ...

Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer

This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This flexible tool offers a detailed observation of chemical gas-phase kinetics in reacting flows under well-controlled conditions. The vast range of operating conditions available in a laminar flow reactor enables access to extraordinary combustion applications that are typically not achievable by flame experiments. These include rich conditions at high temperatures relevant for gasification processes, the peroxy chemistry governing the low temperature oxidation regime or investigations of complex technical fuels. The presented setup allows measurements of quantitative speciation data for reaction model validation of combustion, gasification and pyrolysis processes, while enabling a systematic general understanding of the reaction chemistry. Validation of kinetic reaction models is generally performed by investigating combustion processes of pure compounds. The flow reactor has been enhanced to be suitable for technical fuels (e.g. multi-component mixtures like Jet A-1) to allow for phenomenological analysis of occurring combustion intermediates like soot precursors or pollutants. The controlled and comparable boundary conditions provided by the experimental design allow for predictions of pollutant formation tendencies. Cold reactants are fed premixed into the reactor that are highly diluted (in around 99 vol% in Ar) in order to suppress self-sustaining combustion reactions. The laminar flowing reactant mixture passes through a known temperature field, while the gas composition is determined at the reactors exhaust as a function of the oven temperature. The flow reactor is operated at atmospheric pressures with temperatures up to 1,800 K. The measurements themselves are performed by decreasing the temperature monotonically at a rate of -200 K/h. With the sensitive MBMS technique, detailed speciation data is acquired and quantified for almost all chemical species in the reactive process, including radical species.

An investigation of the oxidative combustion chemistry of novel biofuels, fuel components, or jet fuels by comparison of quantitative speciation data is presented. The data can be used for kinetic model validation and enables fuel assessment strategies.This manuscript describes the atmospheric high-temperature flow reactor and demonstrates its capabilities.

燃料燃烧化学: 用耦合分子束质谱仪从大气高温流反应器中获得的定量形态数据

This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This ...

Reducing Willow Wood Fuel Emission by Low Temperature Microwave Assisted Hydrothermal Carbonization

Biomass is a sustainable fuel, as its CO2 emissions are reintegrated in biomass growth. However, the inorganic precursors in the biomass cause a negative environmental impact and slag formation. The selected short rotation coppice (SRC) willow wood has a high ash content (<img alt="Equation 1" src="/files/ftp_upload/58970/58970eq1.jpg" /> = 1.96%) and, therefore, a high content of emission and slag precursors. Therefore, the reduction of minerals from SRC willow wood by low temperature microwave assisted hydrothermal carbonization (MAHC) at 150 &#176;C, 170 &#176;C, and 185 &#176;C is investigated. An advantage of MAHC over conventional reactors is an even temperature conductance in the reaction medium, as microwaves penetrate the whole reactor volume. This allows a better temperature control and a faster cooldown. Therefore, a succession of depolymerization, transformation and repolymerization reactions can be analyzed effectively. In this study, the analysis of the mass loss, ash content and composition, heating values and molar O/C and H/C ratios of the treated and untreated SCR willow wood showed that the mineral content of the MAHC coal was reduced and the heating value increased. The process water showed a decreasing pH and contained furfural and 5-methylfurfural. A process temperature of 170 &#176;C showed the best combination of energy input and ash component reduction. The MAHC allows a better understanding of the hydrothermal carbonization process, while a large-scale industrial application is unlikely because of the high investment costs.

A protocol for the emission precursor depletion from low quality biomass by low temperature microwave assisted hydrothermal carbonization treatment is presented. This protocol includes the microwave parameters and the analysis of the biocoal product and process water.

低温微波辅助热液碳化降低柳树燃料排放

Biomass is a sustainable fuel, as its CO2 emissions are reintegrated in biomass growth. However, the inorganic precursors in the biomass cause a negative ...

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. ...

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.

聚类诱导解吸/电电质谱法对复杂分子及其在表面的反应分析

Desorption/Ionization Induced by Neutral SO2 Clusters (DINeC) is employed as a very soft and efficient desorption/ionization technique for mass ...

Nitrogen Compound Characterization in Fuels by Multidimensional Gas Chromatography

Certain nitrogen-containing compounds can contribute to fuel instability during storage. Hence, detection and characterization of these compounds is crucial. There are significant challenges to overcome when measuring trace compounds in a complex matrix such as fuels. Background interferences and matrix effects can create limitations to routine analytical instrumentation, such as GC-MS. In order to facilitate specific and quantitative measurements of trace nitrogen compounds in fuels, a nitrogen-specific detector is ideal. In this method, a nitrogen chemiluminescence detector (NCD) is used to detect nitrogen compounds in fuels. NCD utilizes a nitrogen-specific reaction that does not involve the hydrocarbon background. Two-dimensional (GCxGC) gas chromatography is a powerful characterization technique as it provides superior separation capabilities to one-dimensional gas chromatography methods. When GCxGC is paired with a NCD, the problematic nitrogen compounds found in fuels can be extensively characterized without background interference. The method presented in this manuscript details the process for measuring different nitrogen-containing compound classes in fuels with little sample preparation. Overall, this GCxGC-NCD method has been shown to be a valuable tool to enhance the understanding of the chemical composition of nitrogen-containing compounds in fuels and their impact on fuel stability. The % RSD for this method is &#60;5% for intraday and &#60;10% for interday analyses; the LOD is 1.7 ppm and the LOQ is 5.5 ppm.

Here, we present a method utilizing two-dimensional gas chromatography and nitrogen chemiluminescence detection (GCxGC-NCD) to extensively characterize the different classes of nitrogen-containing compounds in diesel and jet fuels.

多维气相色谱在燃料中的氮化合物表征

Certain nitrogen-containing compounds can contribute to fuel instability during storage. Hence, detection and characterization of these compounds is ...

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 ...

Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril

This work describes a rapid and highly sensitive method for the quantitative detection of an important biomarker, uric acid (UA), via surface-enhanced Raman spectroscopy (SERS) with a low detection limit of ~0.2 &#956;M for multiple characteristic peaks in the fingerprint region, using a modular spectrometer. This biosensing scheme is mediated by the host-guest complexation between a macrocycle, cucurbit[7]uril (CB7), and UA, and the subsequent formation of precise plasmonic nanojunctions within the self-assembled Au NP: CB7 nanoaggregates. A facile Au NP synthesis of desirable sizes for SERS substrates has also been performed based on the classical citrate-reduction approach with an option to be facilitated using a lab-built automated synthesizer. This protocol can be readily extended to multiplexed detection of biomarkers in body fluids for clinical applications.

Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril

A host-guest complex of cucurbit[7]uril and uric acid was formed in an aqueous solution before adding a small amount into Au NP solution for quantitative surface-enhanced Raman spectroscopy (SERS) sensing using a modular spectrometer.

通过在金纳米颗粒和葫芦的聚集体中形成精确的等离子体纳米结来定量检测尿酸

This work describes a rapid and highly sensitive method for the quantitative detection of an important biomarker, uric acid (UA), via surface-enhanced ...