"由弗拉芒政府长期结构性玛土撒拉资金"在佛兰德斯研究所创新通过促进科技（IWT）和支持的SBO项目"Bioleum"（IWT-SBO 130039）被确认。

注意:请咨询相关使用前，所有化合物的材料安全数据表（MSDS）。建议适当的安全措施。解决方案和样品应在通风橱，而使用个人防护装备准备。最佳实践意味着使用防护眼镜，防护手套，实验室，实验室外套，全长裤，封闭趾鞋。该反应器应该被适当密封几种反应物和反应产物可以是剧毒和致癌性。 1.离线GC×GC-NCD分析<ol><li> 样品制备离线GC×GC分析 <ol><li>选择-2-氯吡啶作为内标。确保所制备的样品中的内标物的浓度是存在于被分析的混合物含氮化合物的浓度范围内。的内标物的浓度必须低于检测极限ø高至少十倍F中的NCD。此外，内标物的浓度应不低于与样品中浓度最高的氮化合物的浓度高出两倍。 </li><li>制备和使用分析天平称量两片玻璃小瓶中。 </li><li> 20.498毫克2-氯吡啶添加到使用分析天平在第一小瓶中。 </li><li>去皮与第一管形瓶中的平衡，并添加1024.287毫克的页岩油的样品。轻轻地混合小瓶中的内容。 </li><li>转移23.369毫克制备的混合物的成第二小瓶中，并添加435.195毫克原始页岩油的样品。所获得的样品中的内标物浓度是约1,000 ppmw的。 </li></ol></li><li> GC×GC-NCD分析和操作条件 <ol><li>执行使用GC×配备有双级低温液体CO 2的调制器45的GC分析。 <ol><li>连接第一维非极性coluMN（PONA为50μm长×0.25毫米内径×0.5微米D F）直接连接到第二维中等极性柱（BPX-50，2米长×0.25毫米内径×0.25微米D F）。应用在GC×检测包含在页岩油含氮化合物的优化GC操作条件下，用表1中的参数。 </li><li>注入使用自动取样器的样品，在补充表所列的设置。 </li></ol></li><li>为NCD，设定在5和流速11毫升分钟-1的H 2和分别的 O 2，同时保持燃烧温度为1198 K.使用100Hz的数据采集速率。检测器设定在表1中。 </li></ol></li><li> 结果再处理 <ol><li>使用为NCD数据系统进行数据采集。导出原始数据到.CDF文件，并导入到一个分析软件（ 例如，GC图片）。 </li><li>使用分析软件来构造等高线图，以确定保留时间，并根据该软件协议来执行峰拟合和BLOB集成。识别每个斑点作为特定氮基的具有特定碳原子数的化合物。 注意:NCD的响应信号是等摩尔6,46,47,48，因此为含氮化合物的量化过程中，样品是直截了当的。 </li><li>计算使用下面的等式检测化合物的浓度: <img alt="式（1）" src="/files/ftp_upload/54236/54236eq1.jpg" /> 其中V I和V ST是含氮化合物i和内标物的峰体积分别:W ST是内标化合物的浓度，N i是化合物的氮原子的数i，M I和M ST </子&gt;是含有化合物的氮与氮内部标准分别为6的摩尔质量。 </li></ol></li></ol> 2.在线分析<ol><li> 试验厂蒸汽裂解装置 注:试工厂蒸汽裂解装置由三个部分组成:送料段，炉/反应器部分和分析部分。该装置是在别处详细18,49,50,51说明。设置的示意图说明可以在补充信息中找到。 <ol><li>在实验过程中，如庚烷，使用通过设置使用可编程逻辑控制器（PLC）的流量的计算机控制旋转泵送入，通过手动设置在活塞泵的速度引入吡啶向反应器对流段。所用的稀释剂取决于测试的目的，并且可以变化。根据实验的要求，使用氦和氮dilutio气体控制器n和调节蒸汽稀释给水泵的频率。 </li><li>前炉的反应部分，蒸发并在两个分开加热区混合所述原料保持在773 K的温度</li><li>通过设置在使用PLC的五个加热区的温度施以温度分布的镍铬铁合金800HT12.4米长和9mm内径的反应器。不同的实验用不同的工艺条件，可以进行。如表2中所概述使用施加到执行方法测试的过程中的条件。 </li></ol></li><li> 分析方法 <ol><li>使用配有平行通道的工作中，为了检测尽可能多的化合物作为可能的三个检测器的炼厂气体分析仪（RGA）。两个TCD的和FID允许CO，CO 2，H 2和烃的检测多达四个碳原子，使用三种不同的列用于分离反应产物。该RGA设置是PResented于表3中 。 </li><li>为GC×GC调校，在第一维和一个中等极性BPX-50（2米长×0.15毫米编号使用非极性PONA（50 M L x 0.25毫米内径×0.5微米D F）柱×0.15微米D F）列中的第二个维度。确保在烤箱温度可通过添加GC烤箱内液氮降低到233ķ。使用GC×在表4中给出了在线分析的GC设置。 </li><li>确保TOF-MS电子轰击为70伏特和检测器电压1700 V通过在软件中设置这些值。此外采集频率设置为30的光谱/秒中相同的软件15-400原子量的质量范围。 </li><li>为NCD，手动设置为5和流速11毫升分钟-1的H 2和分别的 O 2，同时保持燃烧温度在1198 K的数据采集速率需要是100赫兹。 </li> &lt;LI&gt;对于FID H 2，空气和N 2（化妆气）流速分别为35，350和35ml分钟-1。确保FID温度设定在573 K的100Hz的数据采集速率。 </li><li>品尝试验工厂操作期间上线， 即试工厂流出物，并在高温（673 - 773 K）。使用一个基于阀的采样系统，定位在烘箱保持在573 K时采样，参见图1。 <ol><li>打开气动6端口2路阀，以使用PLC在图1a所示的位置，冲洗样品环为至少2分钟。 </li><li>打开气动6端口2路阀为1b使用PLC，从样品环中的气体样品进行用氦和注射到选定的GC×GC 图中所示的位置。保持在喷射位置的阀20秒。打开气动6端口2路阀回到图1a中所示的位置。 </li> &lt;/ OL&gt; </li></ol></li><li> 内标加入 <ol><li>使用2-氯吡啶作为NCD内标分析。该化合物的导入量取决于实验（ 表2中所示的值）的目的。为了精确且均匀地添加2-氯吡啶，溶解在正己烷（ 表2中所示的值）的化合物和温和搅拌制备后该混合物。 </li><li>通过毛细管输送管线，该中心定位采样系统之前在产品流中抽制备的混合物连续地添加内标2-氯吡啶。为此目的使用一个蠕动泵，并保持流量稳定（值如表2所示）。 </li></ol></li><li> 数据采集和量化 <ol><li>获得与TOF-MS获得的数据，以及用于产品鉴定结果和建立retenti对反应产物的时间。收购并从FID获得的数据再处理类似应用到后处理程序的结果收集使用NCD，如第1.3.2解释。 </li><li>重新计算使用内标18的产品产率。 （N 2）连续地引入氮的固定量的产品流，并使用它作为参考化合物， 如图2。 </li><li>结合在不同的仪器获得的数据。应用校准因子取决于在检测器上的每个化合物。 <ol><li>甲烷校准系数设置为1。 </li><li>获取相对于甲烷对RGA检测永久性气体通过标定响应因子。确保对×GC相对响应因子通过校准确定的GC检测到的所有主要化合物。对于轻微的产品使用由迪茨52报告的FID校准因子。如果响应因子交流ompound不可用，计算利用Dierickx 等人 53研制的基团贡献法的值。 </li><li>甲烷用作次级内标，其浓度是需要的确定基于在GC×GC-FID色谱图的峰浓度。因此决定利用方程2甲烷质量流量: <img alt="公式（2）" src="/files/ftp_upload/54236/54236eq2.jpg" /> 式中，f CH4和F N2分别是甲烷和氮在TCD的校准因素， 一个CH4和A N2是分析过程中获得的峰面积，而<img alt="公式3" src="/files/ftp_upload/54236/54236eq3.jpg" />是添加到流出物流中的氮的质量流率。 </li></ol></li><li>通过应用程序进行含氮产品的定量在第1.3.3解释。 </li></ol></li></o升&gt;

The authors have nothing to disclose.

所描述的实验程序启用一个成功的全面的离线和在线识别和含氮化合物的定量所研究样品英寸含在页岩油化合物氮气分离用的GC×GC-NCD，完成如图3，由于NCD不能用于识别，需要通过进行分析提前建立的观察物种的保留时间在GC×GC耦合 ​​到TOF-MS的基础上，为每个检测方法18,54的载气流量的优化的详细过程。流量适配导致化合物的相似的保留时间，使用不同...

轻质低硫原油储量逐步减弱，因此，正在考虑替代化石资源在能源和石化行业中使用。另外，可再生能源，例如通过生物质的快速热解产生的生物油正在成为生物基燃料和化学品的一个更有吸引力的资源。然而，重质原油是因为在加拿大和委内瑞拉1-3大探明储量的逻辑首选。后者被认为是最大的原油储量在世界上和它们的组合物类似于天然沥青的组合物。向生物油相似，重质原油从光原油可以通过高粘度在贮存温度，高密度（低API比重），和氮，氧的显著内容，和含硫化合物4,5-不同。另一个有希望的替代方案是页岩油，油页岩的。油页岩是一种细粒沉积岩CON泰宁干酪根，有机化学化合物与摩尔质量高达1000达6的混合物。干酪根可以包含有机氧，氮和硫中的烃类基体;视，年龄，和提取条件。全球表征方法已经表明，在页岩油和重质原油的杂原子（S，O和N）的浓度典型地比对用于例如石化行业6的制品设置的规格基本上更高。它是有据可查的，目前的重常规原油和页岩油含氮化合物对在加氢裂化，催化裂化和重整过程7的催化剂活性具有负面影响。类似地，已经报道了含氮化合物的存在是一个安全问题，因为它们促进在蒸汽裂化8的冷箱胶质形成。 这些处理和安全CHALlenges是强烈的驾驶员来提高用于离线和在线含有复杂的碳氢化合物基质化合物氮气表征当前方法。加上一个氮化学发光检测器（NCD）的二维气相色谱（GC×GC）是一种高级的表征技术相比的一维气相色谱（GC），用于分析常规柴油机或液化煤样品7。最近，一个方法已经被开发并在页岩油6施加的氮含量脱机表征，鉴定存在于中间馏分9萃取氮化合物，以及废塑料的热解油10的详细结构的测定。 因此，很明显是GC×GC分析是分析复杂混合物11-17强大的脱机处理技术。然而，上线的应用是更具挑战性，因为需要一个可靠的一个第二非歧视抽样方法。其中第一个发达的方法为全面上线的表征是通过分析利用TOF-MS和FID 18蒸汽裂化反应器污水证明。的GC设置，优化和适当的列组合，启用由碳氢化合物从甲烷到多环芳烃（多环芳烃）18样品的分析。目前的工作由它延伸到存在于复杂的烃类混合物含氮化合物的定性和定量采取这种方法到一个新水平。这样的方法中，以提高这些化合物在一些流程和应用程序所扮演的角色的基本了解需要别人。据作者所知，关于含氮化合物的转化过程中的动力学信息是稀缺的19，部分原因是由于缺乏适当的方法来识别和量化含氮化合物S IN的反应器流出物。建立的方法进行离线和在线分析因此之前甚至可以尝试原料重建20-27和动力学建模的先决条件。其中之一将由含有氮的化合物的准确的鉴定和定量受益字段是蒸汽裂解或热解。生物和重矿物饲料的蒸汽裂解或热解反应器包含数以千计的碳氢化合物和包含杂原子的化合物。此外，由于进料的复杂性和发生化学的自由基性质，可以在数千自由基物质28，这使得即使是比原料更复杂的反应器流出物之间发生数万反应。 在烃类混合物氮主要存在于芳族结构， 例如，吡啶或吡咯;因此，大多数实验的努力一直致力于为这些结构的分解数目字。氰化氢和乙炔被报告为主要产品的温度范围内的1,148-1,323 K.其他产品，如芳族化合物和非挥发性焦油研究吡啶的热分解是在少量的29也检测到。吡咯的热分解，用冲击波实验在更广泛的温度范围1,050-1,450钾调查。主要产物是3-丁烯腈， 顺式和反式 2-丁烯腈，氰化氢，乙腈，2-丙烯腈，丙腈，和丙炔腈30。此外热分解激波管实验在导致同类产品的光谱31,32高温下进行的吡啶。在这些研究中的产品的产量已经被施加GC的配备有FID，氮-磷检测器（NPD）31，质谱仪（MS）32及傅立叶变换红外（FTIR）光谱仪32测定</suP&gt;。类似的方法实施FID和NPD的施加来分析页岩油的热解产物在连续流动反应器8。在273.15说明使用冷阱和GC-MS，Winkler 等33表明，吡啶热解过程中的芳族化合物含杂原子的形成。 Zhang等人 34和德博诺等人 35施加Winkler 等人的方法。用于研究的有机废物的热解。富氮的反应产物进行分析上线，使用耦合到热导检测器（TCD）34为GC。所收集的焦油用GC-MS 34,35离线分析。甲苯和吡啶的同时裂解表明相比吡啶热解在烟灰形成倾向的差值，表示自由基反应31,36的复杂性。 其中一个最全面的分析方法被用N开发ATHAN和同事37。他们用红外光谱，核磁共振（NMR）和GC-MS分析吡啶并二嗪和电子顺磁共振（EPR）光谱的分解产物进行跟踪自由基物种。 FTIR分析可以为大范围的产品的鉴定非常有效的办法，甚至多环芳烃38-40，不过量化是极具挑战性。校准需要在特定的温度和压力下41全套不同浓度为每个目标物种红外光谱。 Hong等的最近的工作证明了吡咯并吡啶分解42,43期间使用分子束质谱（MBMS）和可调谐同步加速器真空紫外光电离测定的产物和中间体的可能性。此实验方法使自由基的异构体的中间体和近阈值检测无INF选择性识别licting所分析的44种碎片。但是，使用MBMS分析测得的浓度的不确定性也很大。 在这项工作中，报道复杂的页岩油的第一个离线的综合表征结果。接着，使用一个在线GC×GC-TOF-MS / FID对在复杂的烃矩阵氮化合物的分析的局限性进行了讨论。最后，对于含有用GC×GC-NCD含氮化合物的在线量化新开发的方法是证明。产品的定性分析进行了使用TOF-MS，而FID和NCD被用于定量。的NCD的应用是相比于使用，因为它的较高的选择性的FID，检测下限和等摩尔反应的显着改进。

<table><tbody><tr><td>2-Chloropyridine, 99%</td><td>Sigma Aldrich</td><td>C69802</td><td>Highly toxic</td></tr><tr><td>Shale oil</td><td>Origin Colorado, US</td><td>Piceance Basin in&lt;br/&gt; Colorado, USA</td><td>Toxic</td></tr><tr><td>Pyridine, 99.8%</td><td>Sigma Aldrich</td><td>270970</td><td>Highly toxic</td></tr><tr><td>Carbon Dioxide, industrial grade refrigerated liquid</td><td>PRAXAIR</td><td>CDINDLB0D</td><td>Wear safety gloves and glasses</td></tr><tr><td>Helium, 99.99%</td><td>PRAXAIR</td><td>6.0</td><td></td></tr><tr><td>Hydrogen, 99.95%</td><td>Air Liquide</td><td>695A-49</td><td>Flammable</td></tr><tr><td>Oxygen</td><td>Air Liquide</td><td>905A-49+</td><td>Flammable</td></tr><tr><td>Air</td><td>Air Liquide</td><td>365A-49X</td><td></td></tr><tr><td>Nitrogen</td><td>Air Liquide</td><td>765A-49</td><td></td></tr><tr><td>Hexane, 95+%</td><td>Chemlab</td><td>CL00.0803.9025</td><td>Toxic</td></tr><tr><td>Heptane, 99+%</td><td>Chemlab</td><td>CL00.0805.9025</td><td>Toxic</td></tr><tr><td>Nitrogen, industrial grade refrigerated liquid</td><td>PRAXAIR</td><td>P0271L50S2A001</td><td>Wear safety gloves and glasses</td></tr><tr><td>Autosampler</td><td>Thermo Scientific, Interscience</td><td>AI/AS 3000</td><td></td></tr><tr><td>High temperature 6 port/2 position valve</td><td>Valco Instruments Company Incorporated</td><td>SSACGUWT</td><td></td></tr><tr><td>Gas chromatograph</td><td>Thermo Scientific, Interscience</td><td>Trace GC ultra</td><td></td></tr><tr><td>Rafinery Gas Analyzer</td><td>Thermo Scientific, Interscience</td><td>KAV00309</td><td></td></tr><tr><td>rtx-1-PONA column</td><td>Restek Pure Chromatography</td><td>10195-146</td><td></td></tr><tr><td>BPX-50 column</td><td>SGE Analytical science</td><td>54741</td><td></td></tr><tr><td>TOF-MS</td><td>Thermo Scientific, Interscience</td><td>Tempus Plus 1.4 SR1 Finnigan</td><td></td></tr><tr><td>NCD</td><td>Agilent Technologgies</td><td>NCD 255</td><td></td></tr><tr><td>Chrom-card</td><td>Thermo Scientific, Interscience</td><td>HyperChrom 2.4.1</td><td></td></tr><tr><td>Xcalibur software</td><td>Thermo Scientific, Interscience</td><td>1.4 SR1</td><td></td></tr><tr><td>Chrom-card software</td><td>Thermo Scientific, Interscience</td><td>HyperChrom 2.7</td><td></td></tr><tr><td>GC image software</td><td>Zoex Corporation</td><td>GC image 2.3</td><td></td></tr></tbody></table>

on-line analysis of nitrogen containing compounds in complex hydrocarbon matrixes

到重质原油的移位和使用替代化石资源如页岩油是石化工业的一个挑战。重质原油和页岩油的组合物而变化基本上取决于混合物的来源。特别是，它们包含含有比常规使用的甜原油的含氮化合物的量增加。氮化合物对在焦化装置和蒸汽裂解发生热过程的操作的影响，并且一些物种被认为是对环境有害的，涉及热解条件下含氮化合物的反应的详细分析提供了有价值的信息。因此，一个新的方法已经开发，并用含有较高的氮含量， 即，页岩油的原料验证。首先，将进料通过加上NITR全二维气相色谱（GC×GC）离线特征蛋白原化学发光检测器（NCD）。在第二步骤中的在线分析方法，开发并通过喂食吡啶溶解在庚烷上的蒸汽裂化试验工厂试验。前者是为最丰富的类中存在的页岩油化合物中的一个有代表性的化合物。将反应器流出物的组合物通过一个内部开发的自动取样系统，随后通过在气相×GC加上时间飞行质谱仪（TOF-MS），火焰电离检测器的样品立即注射法（FID ）和NCD。使用NCD和2-氯吡啶作为内部标准含氮化合物的定量分析的新方法已被开发并展示。

使用脱机的GC×GC-NCD用于容纳页岩油样品中的含氮化合物的表征图3给出所得到的色谱图的下列类进行鉴定:吡啶类，苯胺类，喹啉，吲哚，吖啶，和咔唑。此外，各化合物的细致的量化是可能的。所收集的数据被用于确定个体化合物的浓度，将得到的值列于表5中。在分析样品含有4.21重量主要属于吡啶类含氮化合物的％。从一个加工点这种含氮量高?...

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On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

结合氮化学发光检测全二维气相色谱的方法，已经开发和在一个复杂的烃矩阵施加到含氮化合物的在线分析。

在线含硫化合物在复杂油气矩阵氮分析

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The ...

on-line-analysis-nitrogen-containing-compounds-complex-hydrocarbon

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

10.6K 次观看.  Ghent University. 结合氮化学发光检测全二维气相色谱的方法，已经开发和在一个复杂的烃矩阵施加到含氮化合物的在线分析。 

视频: On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s

N-nitrosamines are a well-established group of environmental carcinogens, which require cytochrome P450 oxidation to exhibit activity. The accepted mechanism of metabolic activation involves formation of &#945;-hydroxynitrosamines that spontaneously decompose to DNA alkylating agents. Accumulation of DNA damage and the resulting mutations can ultimately lead to cancer. New evidence indicates that &#945;-hydroxynitrosamines can be further oxidized to nitrosamides processively by cytochrome P450s. Because nitrosamides are generally more stable than &#945;-hydroxynitrosamines and can also alkylate DNA, nitrosamides may play a role in carcinogenesis. In this report, we describe a general protocol for evaluating nitrosamide production from in vitro cytochrome P450-catalyzed metabolism of nitrosamines. This protocol utilizes a general approach to the synthesis of the relevant nitrosamides and an in vitro cytochrome P450 metabolism assay using liquid chromatography-nanospray ionization-high resolution tandem mass spectrometry for detection. This method detected N&#8242;-nitrosonorcotinine as a minor metabolite of N&#8242;-nitrosonornicotine in the example study. The method has high sensitivity and selectively due to accurate mass detection. Application of this method to a wide variety of nitrosamine-cytochrome P450 systems will help determine the generality of this transformation. Because cytochrome P450s are polymorphic and vary in activity, a better understanding of nitrosamide formation could aid in individual cancer risk assessment.

A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s

&#945;-hydroxylation of carcinogenic nitrosamines by cytochrome P450s is the accepted metabolic pathway that produces DNA-damaging intermediates, which cause mutations. However, new data indicates further oxidation to nitrosamides can occur. We describe a general method for detecting nitrosamides produced from in vitro cytochrome P450-catalyzed metabolism of nitrosamines.

用细胞色素 P450s 检测亚硝胺的体外Nitrosamide 形成的一般方法

N-nitrosamines are a well-established group of environmental carcinogens, which require cytochrome P450 oxidation to exhibit activity. The accepted ...

科研

癌症研究

Improved In-gel Reductive &#946;-Elimination for Comprehensive O-linked and Sulfo-glycomics by Mass Spectrometry

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of biological samples. Similar approaches, that would allow in-depth analysis of the glycans carried by glycoproteins resolved by SDS-PAGE, require special considerations in order to maximize recovery and sensitivity when using mass spectrometry (MS) as the detection method. A major hurdle to be overcome in achieving high-quality data is the removal of gel-derived contaminants that interfere with MS analysis. The sample workflow presented here is robust, efficient, and eliminates the need for in-line HPLC clean-up prior to MS. Gel pieces containing target proteins are washed in acetonitrile, water, and ethyl acetate to remove contaminants, including polymeric acrylamide fragments. O-linked glycans are released from target proteins by in-gel reductive &#946;-elimination and recovered through robust, simple clean-up procedures. An advantage of this workflow is that it improves sensitivity for detecting and characterizing sulfated glycans. These procedures produce an efficient separation of sulfated permethylated glycans from non-sulfated (sialylated and neutral) permethylated glycans by a rapid phase-partition prior to MS analysis, and thereby enhance glycomic and sulfoglycomic analyses of glycoproteins resolved by SDS-PAGE.

In order to comprehensively explore the diversity of O-linked glycans, a new procedure for in-gel reductive &#946;-elimination, combined with permethylation and a rapid phase-partition method, is applied to the analysis of O-linked glycans directly released from glycoproteins resolved by SDS-PAGE and amenable to subsequent glycomic analysis by mass spectrometry.

改善凝胶还原β-消除综合O连接和磺基糖组学质谱

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of ...

化学

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence the oxidizing capacity of the atmosphere through interactions with ozone and hydroxyl radicals. The main sink of NOx is the formation and deposition of nitric acid, a component of acid rain and a bioavailable nutrient. NOx is emitted from a mixture of natural and anthropogenic sources, which vary in space and time. The collocation of multiple sources and the short lifetime of NOx make it challenging to quantitatively constrain the influence of different emission sources and their impacts on the environment. Nitrogen isotopes of NOx have been suggested to vary amongst different sources, representing a potentially powerful tool to understand the sources and transport of NOx. However, previous methods of collecting atmospheric NOx integrate over long (week to month) time spans and are not validated for the efficient collection of NOx in relevant, diverse field conditions. We report on a new, highly efficient field-based system that collects atmospheric NOx for isotope analysis at a time resolution between 30 min and 2 hr. This method collects gaseous NOx in solution as nitrate with 100% efficiency under a variety of conditions. Protocols are presented for collecting air in urban settings under both stationary and mobile conditions. We detail the advantages and limitations of the method and demonstrate its application in the field. Data from several deployments are shown to 1) evaluate field-based collection efficiency by comparisons with in situ NOx concentration measurements, 2) test the stability of stored solutions before processing, 3) quantify in situ reproducibility in a variety of urban settings, and 4) demonstrate the range of N isotopes of NOx detected in ambient urban air and on heavily traveled roadways.

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Previous work suggests that the nitrogen isotopic composition of atmospheric nitrogen oxides might distinguish the influence of different sources in the environment. We report on an automated, mobile, field-based method for the high collection efficiency of atmospheric NOx for N isotopic analysis at an hourly time resolution.

自动化，高清晰度移动采集系统对NO的氮同位素分析<sub系列&gt; X</sub

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence ...

环境科学

Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to characterize. However, to understand the thermodynamic and kinetic controls on greenhouse gas (carbon dioxide [CO2] and methane [CH4]) production resulting from the decomposition of NOM, a molecular-level characterization coupled with microbial proteome analyses is necessary. Further, climate and environmental changes are expected to perturb natural ecosystems, potentially upsetting complex interactions that influence both the supply of organic matter substrates and the microorganisms performing the transformations. A detailed molecular characterization of the organic matter, microbial proteomics, and the pathways and transformations by which organic matter is decomposed will be necessary to predict the direction and magnitude of the effects of environmental changes. This article describes a methodological throughput for comprehensive metabolite characterization in a single sample by direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), gas chromatography mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography mass spectrometry (LC-MS), and proteomics analysis. This approach results in a fully-paired dataset which improves statistical confidence for inferring pathways of organic matter decomposition, the resulting CO2 and CH4 production rates, and their responses to environmental perturbation. Herein we present results of applying this method to NOM samples collected from peatlands; however, the protocol is applicable to any NOM sample (e.g., peat, forested soils, marine sediments, etc.).

This protocol describes a single throughput for complementary analytical and omics techniques culminating in a fully-paired characterization of natural organic matter and microbial proteomics in different ecosystems. This approach permits robust comparisons for identifying metabolic pathways and transformations important for describing greenhouse gas production and predicting responses to environmental change.

用于表征复杂天然有机物混合物的单吞吐量互补高分辨率分析技术

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to ...

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 ...

Early Detection of Cyanobacterial Blooms and Associated Cyanotoxins using Fast Detection Strategy

Fast detection of cyanobacteria and cyanotoxins is achieved using a Fast Detection Strategy (FDS). Only 24 h are needed to unravel the presence of cyanobacteria and related cyanotoxins in water samples and in an organic matrix, such as bivalve extracts. FDS combines remote/proximal sensing techniques with analytical/bioinformatics analyses. Sampling spots are chosen through multi-disciplinary, multi-scale, and multi-parametric monitoring in a three-dimensional physical space, including remote sensing. Microscopic observation and taxonomic analysis of the samples are performed in the laboratory setting, which allows for the identification of cyanobacterial species. Samples are then extracted with organic solvents and processed with LC-MS/MS. Data obtained by MS/MS are analyzed using a bioinformatic approach using the online platform Global Natural Products Social (GNPS) to create a network of molecules. These networks are analyzed to detect and identify toxins, comparing data of the fragmentation spectra obtained by mass spectrometry with the GNPS library. This allows for the detection of known toxins and unknown analogues that appear related in the same molecular network.

A fast-multidisciplinarystrategy for early detection of cyanobacterial blooms and associated cyanotoxins is described here. It allows for the detection of cyanobacteria and related cyanotoxins in water samples and in organic matrices, such as bivalve samples, in 24 h.

使用快速检测策略早期检测蓝藻花和相关氰毒素

Fast detection of cyanobacteria and cyanotoxins is achieved using a Fast Detection Strategy (FDS). Only 24 h are needed to unravel the presence of ...

Workflow Based on the Combination of Isotopic Tracer Experiments to Investigate Microbial Metabolism of Multiple Nutrient Sources

Studies in the field of microbiology rely on the implementation of a wide range of methodologies. In particular, the development of appropriate methods substantially contributes to providing extensive knowledge of the metabolism of microorganisms growing in chemically defined media containing unique nitrogen and carbon sources. In contrast, the management through metabolism of multiple nutrient sources, despite their broad presence in natural or industrial environments, remains virtually unexplored. This situation is mainly due to the lack of suitable methodologies, which hinders investigations.
We report an experimental strategy to quantitatively and comprehensively explore how metabolism operates when a nutrient is provided as a mixture of different molecules, i.e., a complex resource. Here, we describe its application for assessing the partitioning of multiple nitrogen sources through the yeast metabolic network. The workflow combines information obtained during stable isotope tracer experiments using selected 13C- or 15N-labeled substrates. It first consists of parallel and reproducible fermentations in the same medium, which includes a mixture of N-containing molecules; however,a selected nitrogen source is labeled each time. A combination of analytical procedures (HPLC, GC-MS) is implemented to assess the labeling patterns of targeted compounds and to quantify the consumption and recovery of substrates in other metabolites. An integrated analysis of the complete dataset provides an overview of the fate of consumed substrates within cells. This approach requires an accurate protocol for the collection of samples&#8211;facilitated by a robot-assisted system for online monitoring of fermentations&#8211;and the achievement of numerous time-consuming analyses. Despite these constraints, it allowed understanding, for the first time, the partitioning of multiple nitrogen sources throughout the yeast metabolic network. We elucidated the redistribution of nitrogen from more abundant sources toward other N-compounds and determined the metabolic origins of volatile molecules and proteinogenic amino acids.

This protocol describes an experimental procedure to quantitatively and comprehensively investigate the metabolism of multiple nutrient sources. This workflow, based on a combination of isotopic tracer experiments and an analytical procedure, allows the fate of consumed nutrients and the metabolic origin of molecules synthetized by microorganisms to be determined.

基于同位素示踪实验结合的工作流研究多营养源的微生物代谢

Studies in the field of microbiology rely on the implementation of a wide range of methodologies. In particular, the development of appropriate methods ...

生物工程

MALDI-Mass Spectrometric Imaging for the Investigation of Metabolites in Medicago truncatula Root Nodules

Most techniques used to study small molecules, such as pharmaceutical drugs or endogenous metabolites, employ tissue extracts which require the homogenization of the tissue of interest that could potentially cause changes in the metabolic pathways being studied1. Mass spectrometric imaging (MSI) is a powerful analytical tool that can provide spatial information of analytes within intact slices of biological tissue samples1-5. This technique has been used extensively to study various types of compounds including proteins, peptides, lipids, and small molecules such as endogenous metabolites. With matrix-assisted laser desorption/ionization (MALDI)-MSI, spatial distributions of multiple metabolites can be simultaneously detected. Herein, a method developed specifically for conducting untargeted metabolomics MSI experiments on legume roots and root nodules is presented which could reveal insights into the biological processes taking place. The method presented here shows a typical MSI workflow, from sample preparation to image acquisition, and focuses on the matrix application step, demonstrating several matrix application techniques that are useful for detecting small molecules. Once the MS images are generated, the analysis and identification of metabolites of interest is discussed and demonstrated. The standard workflow presented here can be easily modified for different tissue types, molecular species, and instrumentation.

MALDI-Mass Spectrometric Imaging for the Investigation of Metabolites in Medicago truncatula Root Nodules

Mass spectrometric imaging (MSI) is a powerful tool that can be used to discover and identify various chemical species in intact tissues, preserving the compounds in their native environments, which can provide new insights into biological processes. Herein a MSI method developed for the analysis of small molecules is described.&#160;

MALDI-质谱成像代谢物的研究<em&gt;苜蓿</em&gt;根瘤

Most techniques used to study small molecules, such as pharmaceutical drugs or endogenous metabolites, employ tissue extracts which require the ...

生物学

Carbon and Nitrogen Analysis of Environmental Samples

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Elemental Analysis is a method used to determine elemental composition of a material. In environmental samples such as soils, scientists are particularly interested in the amounts of two ecologically important elements, nitrogen and carbon. Elemental analysis by the flash combustion technique works by oxidizing the sample with a catalyst through combustion in a high-temperature chamber. The products of combustion are then reduced to N2 and CO2 and detected with a thermal conductivity detector.
Unlike other methods for total nitrogen determination (Kjeldahl method) and total carbon determination (Walkley-Black, Heanes or Leco methods), the flash combustion technique does not use toxic chemicals and is therefore much safer to use.
This video will demonstrate combustion-based elemental analysis using the Flash EA 1112 instrument from Thermo Fisher Scientific.

碳和氮的环境样品的分析

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Elemental Analysis is a method used to determine elemental composition of a ...

在线含硫化合物在复杂油气矩阵氮分析

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