Name: automated, high-resolution mobile collection system for the nitrogen isotopic analysis of nox
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PKW would like to thank the Voss Environmental Fellowship at Brown University for funding and support. This research was funded by a National Science Foundation CAREER Award (AGS-1351932) to MGH. The authors thank Ruby Ho for her support of this project. The authors would also like to thank Rebecca Ryals; Jim Tang and his research group at the Marine Biological Laboratory, specifically Elizabeth de la Reguera, for access to the LMA-3d and Li-COR 7000 analyzers; Barbara Morin at the Rhode Island Department of Environmental Management; Roy Heaton and Paul Theroux at the Rhode Island Department of Health; Adam McGovern at the Warren Alpert Medical School; and Charlie Vickers and Tom Keifer for collection system machining. We also thank the editorial staff and two anonymous reviewers for their excellent suggested edits that improved the manuscript.

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The authors declare that they have no competing financial interests.

上述协议的细节在溶液介入，从空气样本的字段收集这些解决方案的实验室处理的步骤，以得到浓度和同位素的结果。在这个协议中的关键步骤包括:X分析仪测量结果进行比较NO，解决方案的还原之前的时间最小化。和保持稳定的流量。如果直接中的 NO x浓度的原位测量结果与比较方案，这是非常重要的一个的 NO x分析仪校准相关的所选择的环境和中的NO x浓度的短期变化范围中的较长的时间范围内加以理解集合的解决方案。解决方案NO 3的准确测定-浓度也很重要，无论是对空中的NOx浓度的计算和确定的同位素denitrifie精确的注射量- [R方法。减少样品前溶液稳定性的一段时间是非常重要的，以确保一致的同位素比值。作为该溶液的氧化电势的结果，有可能在溶液中的其它活性氮氧化，最显着的 NH 3，因为它可以在足够高的浓度在某些领域潜在影响的NO 3 -浓度在溶液中。 NH + 4的为NO 3的氧化-预计需要比NO X的氧化长为NO 3 - ，所以它已被建议降低样品（并且因此停止反应）第一天样品收集的范围内。给定可能导致更长的溶液的贮存时间的要求现场条件，溶液的稳定性通过有和没有加入铵检查溶液进行测试。有和没有加入氯化铵，浓缩和同位素值在1＆＃内稳定963;长达一周（ 图3）的不确定性范围（1.5‰）。在取样后两周内，加入或不加入NH + 4溶液是不稳定的，在该NO 3 -在某些情况下，观察的浓度的下降和空白校正不再健壮。尽管预期的NO 3 -可能随时间增加，由于NH + 4氧化，在浓度在某些情况下实际上被观察到降低，这表明两个偶数周后，NH 4 +干涉不造成的不稳定性。因此，解决方案应在一周内被减少，尤其是当采样在以高的 NH 3浓度（ 例如，&gt; 200 ppbv）的环境中进行。最后，它也很关键期间字段集合来记录流速。在入口测得的流率被发现显着变化且难以控制，即使有一个临界ORIF冰在系统中，因为它可以由疏水性过滤器和/或玻璃料的堵塞的影响。建议定期记录的流率（ 例如，在5分钟的间隔）在整个集合的时期，使得空气的随时间收集的每个样品的体积可以精确地确定（参见步骤5）。 有几个备选方案或提出的协议可能修改。例如，该反硝化方法的一个重要优点是在低样品尺寸要求12,13。然而，也可以使用其它同位素的方法。同样地，我们使用浓度的比色测定，但其它方法也可以得到准确的NO 3 -浓度的结果。 在现场收集效率，如在图2中详细描述的，是92±10％。这是至关重要的，以确保有在收集过程中没有分馏。随着收集效率乐SS超过100％，可发生分馏在采集过程中，偏测量所得的同位素比值。在一系列的城市影响的空气条件下，这种新的收集方法的疗效已被证实。 表1列出了外界空气，接近路边，和烟雾腔取样条件下做到这一点，以确定该方法的再现性的多个测试。系统之间的所有同位素比例差异&lt;1.57‰。这表明该方法的范围上的不同取样条件的可重复性。基于场方法具有精度和重现性比在环境（ 图4）中观察到的〜12‰的同位素比的变化显著更好。 该方法的最显著限制是NO 3 -空白或背景与高锰酸钾溶液相关联。各种高锰酸钾类型已经过测试（ 例如 :，晶体，粉末，和储液）4，和包含的所有NO 3 -被暴露在空气中的 NO x前。其结果是，有必要收集到足够的 NO x为NO 3 -溶液中，以达到上述空白的浓度。进一步的研究目前正在进行量化处的样本超过空白浓度最准确的结果的水平。在非常低的环境的 NO x浓度，就可能有必要修改该集合的条件以最大化样品浓度。例如，该流率可提高到收集更多的空气在较短的时间内或溶液体积可以减少，以增加空气与溶液体积并以浓缩空气收集。在任何情况下，该溶液必须保持在收集容器中的玻璃料上方通过该溶液，以保持空气的冒泡。 的 NO x的这个方法收集于同位素分析是现有的方法（ 例如，被动采样器6,17和硫酸和过氧化氢溶液8）在它已被laboratory-和现场验证相对于场适用性，重现性，样品溶液的稳定性，和中是唯一的下的范围内的现场条件集合的效率。 这种新方法是独一无二的它的能力在30-120分钟的时间分辨率积极搜集在环境浓度的现场环境中的 NO x进行同位素分析。它收集在接近100％的效率的 NO x，并已多次证明是该方法的不确定性范围内可再现。在现场收集样品溶液需要被降低之前为最多1周保持稳定。该方法可以收集样品在一定范围的浓度和同位素比率，并且它被示出为可再现从收集到的收集。这种技术可以用来˚F或在各种不同的条件下进行采样，包括在道路上，使用在协议中概述的移动实验室的方法。在NO x的车辆排放的时空变异的解释是一个单独的手稿的主题，在准备 （米勒，DJ 等。2016年J.地球物理。Atmos的，提交）。 未来的抽样包括这种方法到其他类型的 NO x排放量的应用程序（ 例如，微生物产生的土壤和生物质火灾排放）。 同位素跟踪的 NO x源可能方式，但只有当不同来源的签名可以被量化和理解。我们的新方法，能够从各种的 NO x排放源量化的 NO x的同位素组成和直接测试排放的环境的影响是否可以直接定量跟踪。

An erratum was issued for: <a href="https://www-jove-com.bdigitaluss.remotexs.co/video/54962/automated-high-resolution-mobile-collection-system-for-nitrogen">Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx</a>. An author name was updated.
One of the authors&#39; names was corrected from:
Mary O&#39;Conner
to:
Mary O&#39;Connor

An erratum was issued for: <a href="https://www-jove-com.bdigitaluss.remotexs.co/video/54962/automated-high-resolution-mobile-collection-system-for-nitrogen">Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx</a>. An author name was updated.

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

大气中的氮氧化物（NOx = NO + NO 2）是在全球活性氮循环1,2-重要物种。在大气中的 NO x是高度反应性的，并直接有助于向大气的通过其相互作用氧化能力与臭氧（O 3）和羟基自由基（OH）。 的 NO x是从上的小时刻度大气通过氧化为硝酸（HNO 3）或硝酸除去在下部对流层天（NO 3 - ），这两者都是高度可溶，并且可以是干式淀积在气态表面和通过沉淀（ 例如，酸雨）沉积的颗粒气雾剂形式或湿2。 的 NO x是从各种来源，包括燃烧化石燃料，生物质燃烧，在土壤中的微生物过程和闪电射出。源分配是理解的各个源的影响是至关重要的，但不同的来源，它们在空间和时间，和NO x和HNO 3化妆浓度的相对短的寿命变单独分析一个不足度量。稳定同位素可以作为一种方法来更好地跟踪的空间图案和来源时间趋势和NO x的化学和NO 3有用-在环境中，并在大气模型3添加新的限制。迄今为止，用不同的 NO x源相关的同位素特征依然高度不确定，因为以前的方法4大相关的不确定性，尤其是。 以往的研究代表了许多不同的主动和被动的收集方法和产量的报道同位素值大范围的，即使是相同的发射源。菲比格等。发现以前经常使用在他们的效率方面捕获的 NO x大大不同的方法，随着条件的变化大大influ现场接近开关就是嵌入式集合（如温度，湿度，流量，溶液岁）4。以前的NO和NO 2捕获方法的吸收效率不高可能导致分馏。例如，氧化处理14 N相对于15 N率较高可能会产生低偏见δ15 N-NO x的那些不能代表大气值。除了方法问题4,17，各种不同类型的空气采样的也可能有助于在具有相同源相关同位素值报告范围的差异。例如，对于NO x的汽车排放相关联的同位素特征已被建议基于集合在接近公路站点5，交通隧道6，并直接从车辆7,8的排气管。此外，以前的方法有最好的24小时的时间分辨率，并在周围的NOx浓度显著变化按小时（或更短）时间尺度观测到9，可能限制同位素检测了不同来源的应用程序。许多的NO x的收集方法需要能够氧化的 NO x，而且其他收集活性氮（ 例如，铵）非常强氧化溶液，硝酸随着时间的推移，可能造成同位素测量干扰。以前的一些方法也局限于在溶液中，其中仅提供的 NO x的同位素的了解有限，因为它不收集否（初级发射）收集的 NO 2。因此，有必要使用一个一致的，有效的方法，以更好地限制是否中的NO x的同位素的变异性（和NO 3 - ），以捕获从不同排放源的 NO x的环境中，可以用来直接跟踪源和化学。 这对基于字段的NO x的书面报告</sUB&gt;收集技术的同位素分析以必要的时间分辨率，除尘效率（100％），和再现（≤1.5‰），用于在多个场的环境中的应用。该方法中，最初是由菲比格等人所述。 4，进一步通过其收集效率的示范下在现场改变的 NO x和气象条件验证，溶液稳定性和氨干扰的试验，其再现性的在城市环境中的证明。在同位素值时空差异使用，可以高效率地捕获在溶液中的 NO x单laboratory-和现场验证方法研究。本文演示了该方法的近道路，在道路和环境城市空气藏品在30至120分钟的时间分辨率的应用。 简言之， 的 NO x（NO和NO 2）从大气中收集一个高氧化性溶液，作为NO 3 - 。同时，环境的 NO x，NO 2和CO 2的浓度和其它相关数据，诸如GPS位置和收集的时间被记录。样品被收集后，将溶液在实验室中，这涉及到降低溶液使反应停止进行处理，然后中和该溶液的pH为后续NO 3 -浓度和同位素分析。的NO 3 -浓度是通过自动分光光度（ 即，比色）过程在这里确定的。在溶液中到在一个同位素比率质谱仪后续计量气态N 2 O -氮同位素组成是使用反硝化细菌的方法，它定量转换NO 3确定。实验室和现场空白也被收集并作为收藏品的一部分，以确保样品的完整性测量。下面是一个德泰导致一步一步的协议。

<table><tbody><tr><td>Gas Washing Bottle</td><td></td><td></td><td>Custom Design used, numerous companies sell other gas washing bottles. The bottle needs to have a frit inside it.</td></tr><tr><td>Syringe Pump</td><td>Kloehn</td><td>Kloehn Versa Pump 6, 55 Series</td><td></td></tr><tr><td>PTFE Isolation Valves</td><td>Parker</td><td>002-00170-900</td><td>Both 2 three way and double two-way normally closed, electronically actuated valves</td></tr><tr><td>Gas Handling Teflon Tubing</td><td>McMaster Carr</td><td>5033K31</td><td>Quarter inch outer diameter, eigth inch inner diameter, PTFE tubing</td></tr><tr><td>Liquid Handling Tygon Tubing</td><td>McMaster Carr</td><td>5103K32</td><td>Quarter inch outer diameter, eigth inch inner diameter, PTFE tubing</td></tr><tr><td>Compression gas fittings and ball valves (assorted)</td><td>Swagelok</td><td>Assorted</td><td>Stainless Steel</td></tr><tr><td>Flow calibrator</td><td>MesaLabs</td><td>Defender 520</td><td></td></tr><tr><td>Compression PFA fittings</td><td>Cole Parmer</td><td>Assorted</td><td>Gas and liquid handling</td></tr><tr><td>Data Acquisition Board</td><td>National Instruments</td><td>NI USB-6001</td><td>Used for valve switching</td></tr><tr><td>Solid State Relay</td><td>Crydom</td><td>DC60S5</td><td>Used for valve switching</td></tr><tr><td>Single Stage Filter Assembly</td><td>Savillex</td><td>401-21-25-50-21-2</td><td>Use 25 mm and 47 mm diameter holders</td></tr><tr><td>Nylon Membrane Filter</td><td>Pall Corporation</td><td>66509</td><td>1 &amp;mu;m filter, both 25 mm and 47 mm diameter filters</td></tr><tr><td>Hydrophobic Membrane Filter</td><td>Millipore</td><td>LCWP04700</td><td>10.0 &amp;mu;m, 25 mm and 47 mm diameter filters</td></tr><tr><td>Particle Membrane Filters</td><td>Millipore</td><td>FALP04700</td><td>1 &amp;mu;m filter, both 25 mm and 47 mm diameter filters</td></tr><tr><td>Mini Diaphragm Pump</td><td>KNF</td><td>UN 816.1.2 KTP</td><td>Used for stationary lab</td></tr><tr><td>Mini Diaphragm Pump</td><td>KNF</td><td>PJ 26078-811</td><td>Used for mobile lab</td></tr><tr><td>Aluminum</td><td>Onlinemetals.com</td><td>6061-T6</td><td>Cut to size to build system</td></tr><tr><td>Deep Cycle Power Battery</td><td>EverStart</td><td>24DC</td><td></td></tr><tr><td>MilliQ Water</td><td>Millipore</td><td>ZMQSP0DE1</td><td></td></tr><tr><td>Potassium Permanganate 1 N Solution</td><td>Fischer Scientific</td><td>SP282-1</td><td></td></tr><tr><td>Sodium Hydroxide Pellets</td><td>Fischer Scientific</td><td>S318-1</td><td></td></tr><tr><td>Ohaus Benchtop scale</td><td>Pioneer</td><td>EX224N</td><td></td></tr><tr><td>4 ounce Amber Glass Bottles</td><td>Qorpak Bottles</td><td>GLC-01926</td><td>(60 ml and WM 125 ml bottles)</td></tr><tr><td>Amber HDPE Bottles</td><td>Fischerbrand</td><td>300751</td><td>Part number given for 125 ml narrow mouth bottles, Two varieties (125 wide mouth and narrow mouth of some volume)</td></tr><tr><td>Pre-cleaned EPA Amber Wide-mouth Bottle, 500 ml</td><td>Cole Parmer</td><td>EW-99540-55</td><td></td></tr><tr><td>Hydrogen Peroxide 30%</td><td>Fischer Chemical</td><td>H325-500</td><td>Corrosive</td></tr><tr><td>Centrifuge 5810 R</td><td>Eppendorf</td><td>5821020010</td><td></td></tr><tr><td>50 ml Polypropylene Conical Tube</td><td>Falcon</td><td>14-432-22</td><td></td></tr><tr><td>12 N Hydrochloric acid</td><td>Fischer Scientific</td><td>A114SI212</td><td>Corrosive</td></tr><tr><td>Colorimetric Nutrient Analyzer</td><td>Westco Scientific Instruments</td><td>SmartChem 170</td><td>In purchasing the Colorimetric Nutrient Analyzer, this comes with buffers, cleaning solutions, rinse solutions, and solutions for running the instrument, including the solutions to be able to activate the cadmium column in the instrument for nitrate analysis.</td></tr><tr><td>Automatic Titrator</td><td>Hanna Instruments</td><td>HI 901</td><td></td></tr><tr><td>20 ml Clr Headspace Vial</td><td>Microleter, a WHEATON Company</td><td>W225283</td><td>Information listed&amp;nbsp; is for 20 ml vials. 50 ml vials can also be purchased from the vendor listed.</td></tr><tr><td>Septa, 20 mm Gray Butyl Stopper</td><td>Microleter, a WHEATON Company</td><td>20-0025</td><td></td></tr><tr><td>Seal, 20 mm Standard Aluminium</td><td>Microleter, a WHEATON Company</td><td>20-0000AS</td><td></td></tr><tr><td>25 G x 1 1/2 BD PrecisionGlide Needle</td><td>BD</td><td>305127</td><td></td></tr><tr><td>26 G x 1/2 BD PrecisionGlide Needle</td><td>BD</td><td>305111</td><td></td></tr><tr><td>Helium</td><td></td><td>05078-536</td><td>Can order from many different soures</td></tr><tr><td>Crimper/Uncrimper</td><td>WHEATON</td><td>61010-1</td><td></td></tr><tr><td>Isopropanol</td><td>Fischer Chemical</td><td>A459-1</td><td></td></tr><tr><td>Syringes of varying size for mass spec injection</td><td>BD</td><td>Varies based on size</td><td></td></tr><tr><td>Antifoam B Emulsion</td><td>Sigma-Aldrich</td><td>A5757-500ML</td><td></td></tr><tr><td>IRMS</td><td>ThermoFischer Scientific</td><td>IQLAAMGAATFADEMBHW</td><td>The actual isotope ratio mass spectrometer is listed here. Our set up also includes a gas bench and an autosampler.</td></tr><tr><td>Gass Bench II</td><td>ThermoFischer Scientific</td><td>IQLAAEGAATFAETMAGD</td><td></td></tr><tr><td>TriPlus RSH&amp;trade; Autosampler</td><td>ThermoFischer Scientific</td><td>1R77010-0200</td><td>Choose product for headspace injection</td></tr><tr><td>42i NOx Concentration Analyzer</td><td>ThermoFischer Scientific</td><td>101350-00</td><td></td></tr><tr><td>NOx Box</td><td>Drummond Technologies</td><td>LMA-3D/LNC-3D</td><td></td></tr><tr><td>CO&lt;sub&gt;2&lt;/sub&gt; analyzer</td><td>Licor 7000</td><td>7000</td><td></td></tr><tr><td>GPS</td><td>Garmin</td><td>010-00321-31</td><td></td></tr><tr><td>Model 146i Dynamic Gas Calibrator</td><td>ThermoFischer Scientific</td><td>102482-00</td><td></td></tr><tr><td>Model 111 Zero Air Supply</td><td>ThermoFischer Scientific</td><td>7734</td><td></td></tr><tr><td>50.2 ppm NO in N&lt;sub&gt;2&lt;/sub&gt; Gas standard</td><td>Praxis Air</td><td>Will vary with each tank of standard air purchased</td><td></td></tr></tbody></table>

automated, high-resolution mobile collection system for the nitrogen isotopic analysis of nox

氮氧化物（NO x = NO + NO 2）是对环境造成很大影响大气痕量气体的家庭。 的 NO x的浓度，直接通过与臭氧和羟自由基的相互作用影响大气的氧化能力。 的 NO x的主要接收器是形成和硝酸的沉积，酸雨一个组分和生物可利用的营养物。 的 NO x是从自然和人为来源的，这在空间和时间变化的混合物射出。多源的搭配和NO x的短寿命使其具有挑战性的定量限制的不同排放源及其对环境的影响的影响。 NO X的氮同位素已建议之间不同来源的不同，代表一种潜在的有力工具来了解的 NO x的来源和运输。然而，收集大气中以前的方法NO x的长整合了（周月）的时间跨度，不验证了NO x的相关性，不同的野外条件下有效地收集。我们认为，在30分钟和2小时之间的时间分辨率收集同位素分析大气的 NO x一个新的，高效率的场为基础的系统提出报告。该方法收集在溶液中的硝酸，100％效率的气态的 NO x在各种条件。协议都为固定和移动条件下，在城市环境中收集的空气。我们详细介绍的优点，并且该方法的局限性，并证明其在该领域应用。 原位再现性从几个部署数据示为1）评价通过比较场基收集效率与原位 的 NO x浓度测量，2）测试处理前存储溶液的稳定性; 3）量化在各种城市环境，并4）证明N的范围周围城市空气和交通繁忙道路点¯x没有检测到的同位素。

在由菲比格等原始方法的开发工作。中，NO x的收集方法是在实验室严格测试在各种条件4。这里，重点是在各种环境条件下的更新的方法和现场应用。结果列于（1）场的收集效率，（2）在样品还原和灵敏度高浓度的铵的之前的时间方面样品溶液稳定性（NH + 4）的溶液，和（3）再现性在外地。该方法的通用性是表现在其对环境空气，邻近公路应用，并在道路上的测量。 在溶液中收集的平均浓度与那些从1分钟的 NO x浓度从化学发光比较NO X分析仪在多安眠药了为期两天的昼夜研究ŧ城市空气在普罗维登斯，罗得岛。 图2的期间详细描述了收集效率时的浓度变化在大范围内，从大约2.5-18 ppbv 的 NO x。 图2A显示位数的 NO x从与来自溶液和流量测量计算的浓度相比的 NO x分析器浓度的直接比较，这表明，平均来说，溶液的浓度是在原位浓度中位数的92％。此落入±10％的预期的不确定性范围内，但差异可能反映在收集期间（ 图2B）不同浓度。基于1分钟的 NO x浓度数据的分布的百分位数的检查中，基于溶液的NO x的浓度的分布，每收集间隔（ 图2B）内。 它是恩建议完成1天内在现场采集样品的减少收集完成后（即完成所有步骤3）之后。这个目标有人建议减少潜在的从其它可溶性氮物质，如NH 3的集合，能够在高氧化性的KMnO 4 / NaOH溶液在一段时间内转化为硝酸盐干扰。更具体测试，样品收集在五月和2015年7月在普罗维登斯，罗得岛布朗大学的校园里，在装卸码头是不远的地方的柴油运货车经常在空闲模式下卸载运行定期前往当地的道路。收集样品，然后将样品的等分试样中分离，并在样品收集（ 图3A）后不同的时间（1天，4-7天，13-15天）减少。在图3B样品日和月期间，也收集，但通过加入5ml的10mM ammoniu的制备米氯化物450毫升溶液中。这产生111微米NH + 4的浓度在溶液中，对应于在空气中收集的 NH 3 220 ppbv，如果只有NH 3收集。这些浓度在靠近车辆NH 3源16在道路上测量最大期望。有或没有添加的NH + 4，样品7天内相比第一减速时（第1天收集内）后收集具有一致的同位素比率减少，所有落入±1.5％（ 图3A和3B的预期的不确定性范围内）。需要注意的是±1.5％的不确定性代表坦克NO×4的重复收藏的同位素测定的。用同位素标准样品重复测量相关的不确定性单独通常是0.3％。两周后，然而，加入或不加入NH + 4样品不一定稳定。而在一些情况下，同位素值仍显得是一致的（ 例如， 图3A），样品表现出小NO 3 -浓度-浓度的增加（&lt;1μM）当与第一减速和比较，在某些情况下，在NO 3减小。与添加的NH + 4，它会被预期的NO 3 -浓度将随时间增加上述浓度测量的预期的不确定性范围（〜0.8微米），这表明两个偶数周后，将NH + 4不是源的干扰。还需要进一步的实验，以更好地理解这种不稳定的来源，虽然应该注意的是空白溶液不治疗在同一时间过程持续显示没有变化或浓度略有增加，并且因此，不稳定性，必须由其他存在下创建种˚Found在环境城市空气。直到此得到解决，则建议的样品溶液在7天内，从收集的时间减少了。 图4详细样品采集与移动设定了在城市，近道路，在道路上设置的各种现场活动。 NO x的浓度范围跨越三个数量级，并且在同位素比率范围从-1到-13‰。这种采样集包括51采取在道路上的样品超过52小时，占地4000多公里，在行驶条件无数（如重停停走走的交通很轻交通高速在公路上）。采样了在6个主要城市，包括普罗维登斯，罗得岛，费城和宾夕法尼亚州匹兹堡，克利夫兰，哥伦布和辛辛那提之间道路的地方。平均车速范围由12.4公里/小时到119.7公里/小时。近路边的样本（N = 27）在monito获得在I-95现场环普罗维登斯。周围城市空气样本（N =接管117.5小时44样本）从在普罗维登斯，罗得岛，一个I-95附近，I-195交汇处2屋顶的位置，并从现场交流出来的一个775米拍摄。这是朝着建立新的功能，以解决从NOx产生源同位素签名的范围，在这种情况下，车辆的排放和环境城市源的第一步骤。在公路上和道路侧δ15 N-二氮氧化物（ 图4）白天的变化并没有与驱动条件的变化相关，并且跨越相对恒定车辆燃料级交通计数发生。同位素签名由于车辆燃料类型的变化更详细的讨论是另一个手稿（米勒，DJ 等。2016年J.地球物理。Atmos的，提交）的主题。 最后， 表1详细领域和laboratoRY集合，其中两个收集系统被部署在同一时间，以测试再现性。的比较显示了同位素数据，这里量化为每个采集期的两个数据点之间的绝对偏差良好的协议。这些数据来自在普罗维登斯的屋顶位置，城市空气藏品展示;在普罗维登斯近路边收藏;并从马萨诸塞州阿姆赫斯特大学的实验室为基础的烟雾室集合。 <img alt="图1" src="/files/ftp_upload/54962/54962fig1.jpg" /> 图1: 收集原理图和图像。自动化的（A）图的 NO x收集系统。灰色是气流，蓝色是水/液流动，绿色电子产品的连接，黄色的是料和紫色是高锰酸盐的解决方案。注射泵是用于添加和删除冲洗液（超纯水），并用于样品收集的开始添加新溶液（注射泵是市售步进电机注射器泵用50毫升注射器，5端口分配阀，和驱动/控制电路板装备有RS-232串行接口）。样品通过在气体洗涤瓶底部的黑色阀手动删除。 NO x的收集系统和移动实验室的 NO x盒（B）图片。 <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54962/54962fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/54962/54962fig2.jpg" /> 图 2: 自动收集系统的收集效率。 （A）中从NO 3计算出的NO x的浓度-的浓度在溶液中测得的和流量数据免受化学发光的 NO x浓度分析仪在普罗维登斯屋顶现场实测平均浓度进行比较。误差线是从跨越比色浓度测量奔跑和流速的不确定性的质量控制（0.4μM）的合并标准差的传播误差导出的基于溶液的氮氧化物混合比估计的标准偏差（±1σ）（± 1％）。使NO x分析器浓度的不确定性为±5％。 （B）在期间普罗维登斯屋顶网站昼夜测量的时间序列的NOx浓度分布。该方框代表25 日 ，50 日和75 日百分点。胡须代表了极端不离群。 <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54962/54962fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图3: 在5月和2015年七月 （A）， 布朗大学收集 的 NO x 样品的结果被记录为从第一减少，每日1次抽检中执行偏差的减少时间的比较 。可能的样品都显示为三角形和样品七月为圆形，颜色不同的表示采集周期。在（B）中，用氯化铵处理预空气收集之前的样品随时间测试溶液中的NH 4 +的干扰。虚线代表该同位素收集方法的预期总体精确度，表示为±1.5％的标准偏差。 <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54962/54962fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/54962/54962fig4.jpg" /> 图 4:δ15 N-二的 NO x（‰），并 在环境城市空气，在道路上，并且近道路地点采集的样本 的 NO x 浓度。该类型的样品是由不同颜色的划定，并且代表一定范围的条件（见正文）和NO x的浓度。 <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54962/54962fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <table fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td>样品名称</td><td>系统编号</td><td>采集日期</td><td>收集时间</td> &lt;TD&gt;温度（℃） </td><td> [NO 3 - ]（μM） </td><td>空白/总氮</td><td> δ15 N（‰） </td><td>偏差δ15 N（％） </td></tr><tr><td rowspan="2">城市空气PVD 1 </td><td> 1 </td><td rowspan="2"> 2013年10月8日 - 2013年10月9日</td><td rowspan="2"> 6.75 </td><td rowspan="2"> 15.8 </td><td> 14.43 </td><td> 0.3 </td><td> -0.6 </td><td rowspan="2"> 0.7 </td></tr><tr><td> 2 </td><td> 16.78 </td><td> 0.26 </td><td> -1.3 </td></tr><tr><td rowspan="2">城市空气PVD 2 </td><td> 1 </td><td rowspan="2"> 2013年11月6日 - 2013年11月7日</td><td> 2.5 * </td><td rowspan="2"> 17.1 </td><td> 30.86 </td><td> 0.2 </td><td> -7.7 </td><td rowspan="2"> 1 </td></tr><tr><td> 2 </td><td> 5.25 </td><td> 37.05 </td><td> 0.17 </td><td> -6.7 </td></tr><tr><td rowspan="2">城市空气PVD 3 </td><td> 1 </td><td rowspan="2">二零一三年十一月二十〇日 - 2013年11月21日</td><td row跨度="2"&gt; 8.9 </td><td rowspan="2"> 3.28 </td><td> 44.29 </td><td> 0.14 </td><td> -7.1 </td><td rowspan="2"> 0.4 </td></tr><tr><td> 2 </td><td> 29.66 </td><td> 0.21 </td><td> -6.7 </td></tr><tr><td rowspan="2">附近路边1 </td><td> 1 </td><td rowspan="2"> 2014年8月14日 - 2014年8月15日</td><td rowspan="2"> 29 </td><td rowspan="2"> 19.2 </td><td> 13.3 </td><td> 0.37 </td><td> -9.47 </td><td rowspan="2"> 0.69 </td></tr><tr><td> 2 </td><td> 16.4 </td><td> 0.3 </td><td> -10.16 </td></tr><tr><td rowspan="2">附近路边2 </td><td> 1 </td><td rowspan="2"> 2014年8月17日 - 2014年8月18日</td><td rowspan="2">三十</td><td rowspan="2"> 21.85 </td><td> 9.4 </td><td> 0.68 </td><td> -8.95 </td><td rowspan="2"> 1.56 </td></tr><tr><td> 2 </td><td> 11.6 </td><td> 0.55 </td><td> -7.39 </td></tr><tr><td rowspan="2">附近路边3 </td><td> 1 </td><td rowspan="2"> 2015年5月25日</td><td rowspan="2"> 3.5 &lt;/ TD&gt; <td rowspan="2"> 20 </td><td> 6.86 </td><td> 0.51 </td><td> -7.67 </td><td rowspan="2"> 0.86 </td></tr><tr><td> 2 </td><td> 9.49 </td><td> 0.42 </td><td> -8.53 </td></tr><tr><td rowspan="2">附近路边4 </td><td> 1 </td><td rowspan="2"> 2015年5月26日</td><td rowspan="2"> 2.75 </td><td rowspan="2"> 25.56 </td><td> 6.07 </td><td> 0.656 </td><td> -8.7 </td><td rowspan="2"> 1.57 </td></tr><tr><td> 2 </td><td> 6.49 </td><td> 0.61 </td><td> -7.13 </td></tr><tr><td rowspan="2">烟雾箱1 </td><td> 1 </td><td rowspan="2"> 2014年8月26日 - 2014年8月27日</td><td rowspan="2"> 24.4 </td><td rowspan="2"> 21 </td><td> 24.392 </td><td> 0.27 </td><td> -12.28 </td><td rowspan="2"> 0.33 </td></tr><tr><td> 2 </td><td> 33.2 </td><td> 0.2 </td><td> -12.61 </td></tr><tr><td rowspan="2">烟雾箱2 </td><td> 1 </td><td rowspan="2"> 2014年8月27日 - 2014年8月28日</td><td rowspan="2"> 19.8 </td> &lt;TD行跨度="2"&gt; 21 </td><td> 10.96 </td><td> 0.54 </td><td> -10.22 </td><td rowspan="2"> 1.25 </td></tr><tr><td> 1 </td><td> 14.245 </td><td> 0.41 </td><td> -11.47 </td></tr><tr><td>烟雾箱3 </td><td> 1 </td><td> 2014年8月28日 - 2014年8月29日</td><td> 24.2 </td><td> 21 </td><td> 7.476 </td><td> 0.8 </td><td> -5.86 </td><td> 1.27 </td></tr></tbody></table> 表1:使用两个完全相同的收集系统同时收集的样本的可重复性。 *收集了因停下来过滤器堵塞。城市空气PVD（物理气相沉积=普罗维登斯）1-3以前公布4。附近路边代表普罗维登斯路边收藏;烟雾箱代表马萨诸塞州阿姆赫斯特4的大学从空气中收集烟雾室内样品。

Watch this Scientific Journal Video about Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx at JoVE.com

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 ...

automated-high-resolution-mobile-collection-system-for-nitrogen

Universidad San Sebastian

Research

JoVE Journal

Environment

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

11.5K 次观看.  Brown University. 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.

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

Procedures of Laboratory Fumigation for Pest Control with Nitric Oxide Gas

Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control. This paper provides detailed protocols for conducting NO fumigation on fresh products and procedures for residue analysis and product quality evaluation. An airtight fumigation chamber containing fresh fruit and vegetables is first flushed with nitrogen (N2) to establish an ultralow oxygen (ULO) environment followed by injection of NO. The fumigation chamber is then kept at a low temperature of 2 - 5 &#176;C for a specified time period necessary to kill a target pest to complete a fumigation treatment. At the end of a fumigation treatment, the fumigation chamber is flushed with N2 to dilute NO prior to opening the chamber to ambient air to prevent the reaction between NO and O2, which produces NO2 and may damage delicate fresh products. At different times after NO fumigation, NO2 in headspace and nitrate and nitrite in liquid samples were measured as residues. Product quality was evaluated after 2 weeks of post-treatment cold storage to determine effects of NO fumigation on product quality. Keeping&#160;O2 from reacting with NO is critical to NO fumigation and is an important part of the protocols. Measuring NO levels is challenging and a practical solution is provided. Possible protocol modifications are also suggested for measuring NO levels in the fumigation chambers as well as residues. NO fumigation has the potential to be a practical alternative to methyl bromide fumigation for postharvest pest control on fresh and stored products. This publication is intended to assist other researchers in conducting NO fumigation research for postharvest pest control and accelerating the development of NO fumigation for practical applications.

This paper describes nitric oxide (NO) fumigation protocols for postharvest pest control. Fumigation chambers are flushed with nitrogen (N2) to establish ultralow oxygen conditions before NO is injected. At the end, chambers are flushed with N2 to dilute NO before exposing products to ambient air to prevent exposure to NO2.

一氧化氮气体防治害虫实验室熏蒸程序

Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control. This paper provides detailed protocols for conducting NO fumigation on ...

科研

环境科学

Analytical Techniques for Assaying Nitric Oxide Bioactivity

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be considered one of the most important signaling molecules produced in our body, regulating essential functions including but not limited to regulation of blood pressure, immune response and neural communication. Therefore its accurate detection and quantification in biological matrices is critical to understanding the role of NO in health and disease. With such a short physiological half life of NO, alternative strategies for the detection of reaction products of NO biochemistry have been developed. The quantification of relevant NO metabolites in multiple biological compartments provides valuable information with regards to in vivo NO production, bioavailability and metabolism. Simply sampling a single compartment such as blood or plasma may not always provide an accurate assessment of whole body NO status, particularly in tissues. The ability to compare blood with select tissues in experimental animals will help bridge the gap between basic science and clinical medicine as far as diagnostic and prognostic utility of NO biomarkers in health and disease. Therefore, extrapolation of plasma or blood NO status to specific tissues of interest is no longer a valid approach. As a result, methods continue to be developed and validated which allow the detection and quantification of NO and NO-related products/metabolites in multiple compartments of experimental animals in vivo. The established paradigm of NO biochemistry from production by NO synthases to activation of soluble guanylyl cyclase (sGC) to eventual oxidation to nitrite (NO2-) and nitrate (NO3-) may only represent part of NO's effects in vivo. The interaction of NO and NO-derived metabolites with protein thiols, secondary amines, and metals to form S-nitrosothiols (RSNOs), N-nitrosamines (RNNOs), and nitrosyl-heme respectively represent cGMP-independent effects of NO and are likely just as important physiologically as activation of sGC by NO. A true understanding of NO in physiology is derived from in vivo experiments sampling multiple compartments simultaneously. Nitric oxide (NO) methodology is a complex and often confusing science and the focus of many debates and discussion concerning NO biochemistry. The elucidation of new mechanisms and signaling pathways involving NO hinges on our ability to specifically, selectively and sensitively detect and quantify NO and all relevant NO products and metabolites in complex biological matrices. Here, we present a method for the rapid and sensitive analysis of nitrite and nitrate by HPLC as well as detection of free NO in biological samples using in vitro ozone based chemiluminescence with chemical derivitazation to determine molecular source of NO as well as ex vivo with organ bath myography.

The endogenous production of nitric oxide (NO) regulates a wide variety of biological functions. It is becoming increasingly clear that disruption or dysregulation of NO based signaling is involved in many human diseases. Methods to quantify relevant NO metabolites may provide novel diagnostic or prognostic biomarkers for human disease.

为含量测定一氧化氮生物活性分析技术

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be ...

医学

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

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 composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC &#215; GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.

A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

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 ...

化学

Detection of 3-Nitrotyrosine in Atmospheric Environments via a High-performance Liquid Chromatography-electrochemical Detector System

3-nitrotyrosine (3-NT) is generated from the tyrosine residue in atmospheric bio-aerosol proteins via a reaction with ozone (O3) and nitrogen dioxide (NO2). Stable 3-NT is a specific marker for oxidative damage and is reported to have a promotive effect to elicit allergies. In the present study, we report the development of a highly sensitive assay to quantify 3-NT in air sampler filters to collect &#60; 2.5 &#181;m of particulate matter (PM2.5) from urban environmental air, including bio-aerosol. In this method, a 6 mm-diameter round hole was cut from the filters of air samplers and mixed with a nonspecific protease cocktail in order to hydrolyze proteins. Protein samples digested to the amino acid level were tested for 3-NT using a high-performance liquid chromatography-electrochemical detector (HPLC-ECD). The maximum 3-NT content was detected in a prefilter for PM of sizes from 4.5 to 7.3 &#956;m, with a detection limit of 1.13 pg/m3.

Detection of 3-Nitrotyrosine in Atmospheric Environments via a High-performance Liquid Chromatography-electrochemical Detector System

We present a method to detect 3-nitrotyrosine chemical modifications of atmospheric proteins with 6 mm-diameter rounds cut from air sampler prefilters using a high-performance liquid chromatography-electrochemical detector (HPLC-ECD).

利用高效液相色谱-电化学检测仪检测大气环境中的 3-硝基酪氨酸

3-nitrotyrosine (3-NT) is generated from the tyrosine residue in atmospheric bio-aerosol proteins via a reaction with ozone (O3) and nitrogen dioxide ...

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

The importance of understanding the fate of nitrate (NO3&#8722;), which is the dominant N species transferred from terrestrial to aquatic ecosystems, has been increasing because global nitrogen loads have dramatically increased following industrialization. Dissimilatory nitrate reduction to ammonium (DNRA) and denitrification are both microbial processes that use NO3&#8722; for respiration. Compared to denitrification, quantitative determinations of the DNRA activity have been carried out only to a limited extent. This has led to an insufficient understanding of the importance of DNRA in NO3&#8722; transformations and the regulating factors of this process. The objective of this paper is to provide a detailed procedure for the measurement of the potential DNRA rate in environmental samples. In brief, the potential DNRA rate can be calculated from the 15N-labeled ammonium (15NH4+) accumulation rate in 15NO3&#8722; added incubation. The determination of the 14NH4+ and 15NH4+ concentrations described in this paper is comprised of the following steps. First, the NH4+ in the sample is extracted and trapped on an acidified glass filter as ammonium salt. Second, the trapped ammonium is eluted and oxidized to NO3&#8722; via persulfate oxidation. Third, the NO3&#8722; is converted to N2O via an N2O reductase deficient denitrifier. Finally, the converted N2O is analyzed using a previously developed quadrupole gas chromatography&#8211;mass spectrometry system. We applied this method to salt marsh sediments and calculated their potential DNRA rates, demonstrating that the proposed procedures allow a simple and more rapid determination compared to previously described methods.

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

A series of methods to determine the potential DNRA rate based on 14NH4+/15NH4+ analyses is provided in detail. NH4+ is converted into N2O via several steps and analyzed using quadrupole gas chromatography&#8211;mass spectrometry.

基于14NH 4 + /4+ 15NH 4= 通过顺序转换为 N2O 的分析，测量异化硝酸盐降低至铵的潜在率

The importance of understanding the fate of nitrate (NO3&#8722;), which is the dominant N species transferred from terrestrial to aquatic ecosystems, has ...

Microplot Design and Plant and Soil Sample Preparation for 15Nitrogen Analysis

Many&#160;nitrogen fertilizer studies evaluate the overall effect of a treatment on end-of-season measurements such as grain yield or cumulative N losses. A stable isotope approach is necessary to follow and quantify the fate of fertilizer derived N (FDN) through the soil-crop system. The purpose of this paper is to describe a small-plot research&#160;design utilizing non-confined 15N enriched microplots for multiple soil and plant sampling events over two growing seasons and provide sample collection, handling, and processing protocols for total 15N analysis. The methods were demonstrated using a replicated study from south-central Minnesota planted to corn (Zea mays L.). Each treatment consisted of six corn rows (76 cm row-spacing) 15.2 m long with a microplot (2.4 m by 3.8 m) embedded at one end. Fertilizer-grade urea was applied at 135 kg N&#8729;ha-1 at planting, while the microplot received urea enriched to 5 atom % 15N. Soil and plant samples were taken several times throughout the growing season, taking care to minimize cross-contamination by using separate tools and physically separating unenriched and enriched samples during all procedures. Soil and plant samples were dried, ground to pass through a 2 mm screen, and then ground to a flour-like consistency using a roller jar mill. Tracer studies require additional planning, sample processing time and manual labor, and incur higher costs for 15N enriched materials and sample analysis than traditional N studies. However, using the mass balance approach, tracer studies with multiple in-season sampling events allow the researcher to estimate FDN distribution through the soil-crop system and estimate unaccounted-for FDN from the system.

Microplot Design and Plant and Soil Sample Preparation for 15Nitrogen Analysis

A microplot design for 15N tracer research is described to accommodate multiple in-season plant and soil sampling events. Soil and plant sample collection and processing procedures, including grinding and weighing protocols, for 15N analysis are put forth.

微图设计及植物和土壤样品制备，进行15次氮气分析

Many&#160;nitrogen fertilizer studies evaluate the overall effect of a treatment on end-of-season measurements such as grain yield or cumulative N losses. ...

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 ...

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds

Nitric oxide (NO) activity in vivo is the combined results of its direct effects, the action of its derivatives generated from NO autoxidation, and the effects of nitrosated compounds. Measuring NO metabolites is essential to studying NO activity both at vascular levels and in other tissues, especially in the experimental settings where exogenous NO is administered. Ozone-based chemiluminescence assays allow precise measurements of NO and NO metabolites in both fluids (including plasma, tissue homogenates, cell cultures) and gas mixtures (e.g., exhaled breath). NO reacts with ozone to generate nitrogen dioxide in an excited state. The consequent light emission allows photodetection and the generation of an electric signal reflecting the NO content of the sample. Aliquots from the same sample can be used to measure specific NO metabolites, such as nitrate, nitrite, S-nitrosothiols, and iron-nitrosyl complexes. In addition, NO consumed by cell-free hemoglobin is also quantified with chemiluminescence analysis. An illustration of all these techniques is provided.

Here, we present protocols for detecting nitric oxide and its biologically relevant derivatives using chemiluminescence-based assays with high sensitivity.

基于化学发光的检测方法，用于检测自氧化和亚硝化化合物中的一氧化氮及其衍生物

Nitric oxide (NO) activity in vivo is the combined results of its direct effects, the action of its derivatives generated from NO autoxidation, and the ...

Measuring Nitrite and Nitrate, Metabolites in the Nitric Oxide Pathway, in Biological Materials using the Chemiluminescence Method

Nitric oxide (NO) is one of the main regulator molecules in vascular homeostasis and also a neurotransmitter. Enzymatically produced NO is oxidized into nitrite and nitrate by interactions with various oxy-heme proteins and other still not well known pathways. The reverse process, reduction of nitrite and nitrate into NO had been discovered in mammals in the last decade and it is gaining attention as one of the possible pathways to either prevent or ease a whole range of cardiovascular, metabolic and muscular disorders that are thought to be associated with decreased levels of NO. It is therefore important to estimate the amount of NO and its metabolites in different body compartments &#8212; blood, body fluids and the various tissues. Blood, due to its easy accessibility, is the preferred compartment used for estimation of NO metabolites. Due to its short lifetime (few milliseconds) and low sub-nanomolar concentration, direct reliable measurements of blood NO in vivo present great technical difficulties. Thus NO availability is usually estimated based on the amount of its oxidation products, nitrite and nitrate. These two metabolites are always measured separately. There are several well established methods to determine their concentrations in biological fluids and tissues. Here we present a protocol for chemiluminescence method (CL), based on spectrophotometrical detection of NO after nitrite or nitrate reduction by tri-iodide or vanadium(III) chloride solutions, respectively. The sensitivity for nitrite and nitrate detection is in low nanomolar range, which sets CL as the most sensitive method currently available to determine changes in NO metabolic pathways. We explain in detail how to prepare samples from biological fluids and tissues in order to preserve original amounts of nitrite and nitrate present at the time of collection and how to determine their respective amounts in samples. Limitations of the CL technique are also explained.

Nitric oxide (NO) is an important signaling molecule in vascular homeostasis. NO production in vivo is too low for direct measurement. Chemiluminescence provides useful insight into NO cycle via measuring its precursors and oxidation products, nitrite and nitrate. Nitrite / nitrate determination in body tissues and fluids is explained.

用化学发光法测定硝酸盐和亚硝酸盐，代谢产物中的一氧化氮途径，在生物材料

Nitric oxide (NO) is one of the main regulator molecules in vascular homeostasis and also a neurotransmitter. Enzymatically produced NO is oxidized into ...

生物学

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen dioxide (NO2):
NO2 + sunlight &#8594; NO + O
O + O2 &#8594; O3
Ozone (O3) can go on to react with nitric oxide (NO) to form nitrogen dioxide (NO2) and oxygen:
NO + O3 &#8594; NO2 + O2
This results in no net gain of ozone (O3). However, with the anthropogenic production of ozone forming precursors (NO, NO2, and volatile organic compounds) through the combustion of fossil fuels, elevated levels of ozone in the troposphere have been found. Motor vehicle exhaust is a significant source of these ozone forming precursors: NO, NO2, and volatile organic compounds (VOCs). For example, mobile sources make up nearly 60% of NO + NO2 emissions.
At the high temperatures found in a car&#8217;s combustion chamber, nitrogen and oxygen from the air react to form nitric oxide (NO) and nitrogen dioxide (NO2):
N2(g) + O2 (g)&#8594; 2 NO(g)
2 NO(g) + O2(g)&#8594; 2 NO2(g)
The nitric oxide (NO) emitted in the car exhaust is gradually oxidized to nitrogen dioxide (NO2) in ambient air. This mixture of NO and NO2 is often referred to as NOx. When NOx reacts with volatile organic compounds in the atmosphere in the presence of sunlight, tropospheric ozone forms, as seen in this simplified chemical reaction:
NOx + VOCs + sunlight &#8594; O3 + other products
This noxious mixture of air pollution, which can include aldehydes, peroxyacetyl nitrates, ozone, VOCs, and NOx, is called photochemical smog. Ozone is the largest component of photochemical smog. This smog is found in all modern cities, but it&#8217;s found especially in cities with sunny, warm, dry climates and large numbers of motor vehicles. The yellow-brown color of smog in the air is due in part to the nitrogen dioxide present, since this gas absorbs visible light near 400 nm (Figure 1).
Short-term NO2 exposure (30 min to 1 day) leads to adverse respiratory effects in healthy people and increased respiratory symptoms in people with asthma. NOx reacts with ammonia and other compounds to form particulates. These small particles can penetrate the lungs and cause respiratory problems, including emphysema and bronchitis. Individuals who spend a lot of time on the road or who live near a roadway experience considerably higher exposure to NO2.
Due to the impact it has on human health and the environment, the U.S. Environmental Protection Agency (EPA) has classified NO2 as a criteria pollutant and has set the primary standard at 100 ppb (98th percentile of 1-h daily maximum concentrations, averaged over 3 years) and 53 ppb (annual mean). Considering that on-road vehicles account for approximately 1/3 of NOx emissions in the U.S., automobile emissions are therefore regulated through the Clean Air Act. The U.S. EPA established emission standards that automobile manufacturers must follow when producing cars. Currently, Tier 2 emission standards set that manufacturers must have fleet average NOx emissions of no more than 0.07 g/mile.
One way manufacturers meet this standard is by using catalytic converters on their cars. This device is placed between the engine and the tailpipe. The exhaust stream passes through the catalytic converter and is exposed to a catalyst. A reduction catalyst of platinum and rhodium is used to reduce the NOx concentration in the exhaust. When an NO or NO2 molecule in the exhaust contacts the catalyst, the nitrogen atom is grabbed off the molecule and held onto by the catalyst. The oxygen is freed and forms O2. The nitrogen atom on the catalyst binds with another nitrogen atom held on the catalyst to form N2.
Catalytic converters have greatly reduced the emissions of NOx from car exhaust &#8211; up to 80% reduction, when performing properly. However, they only work when they have reached a fairly high temperature. Therefore, when doing a cold start of a car, the catalytic converter is removing virtually no NOx. It isn&#8217;t until the catalytic converter reaches higher temperatures that it effectively removes the NOx from the exhaust stream. Catalytic converters do not work on diesel passenger cars due to the lean conditions under which they operate. In addition, the sulfur in diesel fuel also deactivates the catalyst. The NOx in diesel engines are reduced mainly through the exhaust gas recirculation (EGR) valve, which cools the temperature of the combustion gases. As a result, diesel cars generally emit more NOx than gasoline cars.
<img alt="Figure 1" src="/files/ftp_upload/10076/10076fig1.jpg" /> 
Figure 1. Characteristic coloration for smog in California in the beige cloud bank behind the Golden Gate Bridge. The brown coloration is due to the NOx in the photochemical smog.

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

没有x在汽车尾气利用紫外-可见光谱法测定

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen ...

自动化，高清晰度移动采集系统对NO的氮同位素分析

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