Name: standardized method for measuring collection efficiency from wipe-sampling of trace explosives
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杰恩莫罗博士和桑德拉·达席尔瓦博士，无论是从NIST，促成了该方法的早期版本。美国国土安全部，美国能源部的科学与技术局主办的生产这种材料的一部分的下间协议HSHQPM-15-T-00050与美国国家标准与技术研究院（NIST）。

1.仪器<ol><li>选择或制造器件与可移动的平面（参见图1中示意）。 注意:在此，使用TL-滑动/剥离测试仪但该器件的功能，如摩擦力的测定，即是没有必要在该方法中，并且可以增加成本通过简单的装置。 <ol><li>选择平面尺寸与由3cm的最小宽度为15厘米的最小长度。长度控制为单个采样路径（ 图1）的最大行进距离。 </li><li>选择与一个重复性在±10％的选定的速度移动以定义的速度从50-400毫米/秒的平面。范围是基于来自一个志愿者人口进行擦拭实验数据。 10 </li></ol></li><li>制造擦拭物夹持器（ 图2）。在补充资料CAD图纸。 <ol><li>包括夹紧机构保持擦拭暴露circulAR收集区直径30毫米。收集区是基于那里仪器的解吸区定义允许的收集区典型的ETD。 </li><li>包括收集区域后面可拆卸的软后盾，提供给偶数的动力分配。这是在污染的情况下，可以不另外通过清洗去除可拆卸。背衬可以由海绵橡胶的泡沫，如ASTM D1894 14，或另一种软的材料所描述的，如毛毡，切割成适当的尺寸。 注:在ASTM D1894中描述的海绵橡胶的性能包括:使用85±15千帕（12.5±2.5 psi）的压力时，以压缩泡沫的25％的能力来测量所需的柔软性。我们评估任何背衬材料的有效性通过使用力敏感膜8，10映射压力均匀地分布力。在整个收集区（压力30毫米 diame之三圆）可基于只针对受力均匀分布的总力来计算。 </li><li>包括在擦拭范围从约1至15 N（约100至1500克力）附接权重，以提供总的力（保持器和重量的组合重量）。在擦拭支架的重量设定最小力。力范围是基于数据从志愿者人口进行擦拭的实验中，其中平均力施加为7 N. 10的最大的力将通过确保行驶期间在表面上平滑运动的能力的限制。 </li><li>包括眼钩或类似装置用于连接一个约束线。导线抑制从平面的运动期间移动擦拭支架。导线应平行于表面或平面的运动期间处于轻微的正角。 </li></ol></li></ol> 2.材料的选择和仪器配置<ol><li>选择TE基于相似甄别环境ST表面。选择可包括合成皮革，金属，塑料，纸板，织物，即是平的，适合于测试装置的平面等使用的表面。非常灵活的表面可能需要由刚性表面进行备份，以防止擦拭采样过程中发生移动。 <ol><li>如果必要的话，清洁的溶剂（乙醇或甲醇通常是合适的）和/或通过吹离颗粒加压空气切割表面的尺寸。清洁表面之前立即擦拭取样的行为。 </li></ol></li><li>使用自认为是在擦拭取样用任何材料制成的湿巾。他们必须有最小尺寸覆盖在擦拭支架30毫米直径的圆形收集区和到位夹紧。 <ol><li>切湿巾的大小，如果需要放入抹持有人。 </li><li>测试中使用的第4节中描述以下过程来确定提取效率和空白铅污染之前的擦拭物的一个子集离子水平相对于RDX或其它污染物可能会干扰分析。 </li></ol></li><li>准备通过喷墨印刷阵列RDX粒子标准到聚四氟乙烯（PTFE）的基板。它们的制造和使用进行了详细审查的出版物中描述。 RDX 200ng的是最小量，给定的大约5纳克/毫升，并且最大量的定量技术的基础上，在指纹报告金额RDX的典型的分析检测限，应该是一个几微克。样品可以在冷藏条件下打印后举行长达30天。 注意:从这些标准获得的颗粒的尺寸范围为1微米至40微米的直径，模拟以及在处理塑料炸药12之后进行指纹的颗粒。转移的样品的面积分布取决于印刷阵列大小，但通常是一个5毫米的5mm的区域内;以及内30毫米直径的圆形采样区域。该协议使用通过当转印到测试表面具有已知的粒度分布和已知的区域分布喷墨打印产生RDX粒子标准。其它干转移样品13能如果相同的参数是已知的使用。不推荐通过直接沉积溶液到测试表面产生样本。 </li><li>配置和用于擦拭取样试验装置。 <ol><li>移动面上的起点位置（ 图1）。 </li><li>参照图3，放置一个测试表面，而不粘附它，该设备平面上。 <ol><li>从纸制备的模板，如在图1中的示意图中所示，并把它齐平，以在测试表面的边缘， 如图3。模板标志着擦拭开始位置和采样路径的位置和长度的位置。 </li><li>坚持在型板T○表面使用磁带。移动表面，与模板，来回上飞机，直到擦坐在起始位置时，限制线绷紧。移动的表面上，与模板，侧面到侧面的平面上，直到约束丝的中心向下的行进路径。 </li></ol></li><li>标记上，其中底物将被粘附，如上文所确定的平面的位置。坚持面，与模板，使用双面胶带的平面。 </li><li>使用软件控制的仪器输入行驶距离和行驶速度。 </li><li>发起的平面的运动，以测试该擦拭遵循的整个行驶距离的采样路径，以确保顺利的旅行。 注:的一些组合擦拭和测试表面可导致运动期间高水平的摩擦。跳跃和运动期间的擦拭起重是不希望的。该擦拭巾可从长行程的采样通道或某些偏离组合的擦拭和测试表面。最关键的因素是，以确保通过样品沉积位置擦拭通行证。调整限制线的角度可能有助于缓解这一问题。 </li><li>从样品测量存款行程的末端的位置的行进距离。 注:如果在样品在图1中放置采样路径的起点附近，如，行驶距离将处于其最大的测试表面的长度。较小的行进距离可以通过限制行驶的总长度来选择，或者通过移动所述样品的位置。 </li></ol></li></ol> 3.擦拭取样<ol><li>清洁测试表面并晾干。 </li><li>放置在顶加载天平表面，在上面放置一纸模板（参见2.4.2），在转角保持到位。 </li><li>拿在手上的颗粒样品，并使用掠照明来检查阵列完成。 </li><li>将手指存款的背后并把PTFE基板存款侧向下测试表面上，与所述标记的样品区域内的沉积物。沿着平移使用最少的10N的采样路径中的测试表面的PTFE基板（观察的重量上的平衡，以等于或超过千克力），以干转移的粒子。 <ol><li>对于具有条纹纹理测试表面，翻译沿表面垂直于条纹的PTFE基板，即使这是正交于采样路径。 </li></ol></li><li>使用掠照明检查干转印后的PTFE基板，以确保移除阵列。如果数组元素仍然存在，选择是否继续或放弃实验，重新开始。的选择将取决于从提取和分析，并在需要的表面上的最小质量的检测限。 </li><li>保留PTFE基材的转印效率的提取和判定。 </li><li>将测试表面上的平面在previously定义的位置，并坚持使用双面胶或等效的平面。 </li><li>加载所选抹到支架和附加适当的权重选择的力量。 </li><li>记录温度和湿度的实验附近在±2℃和±5％RH。 </li><li>附加约束丝的擦拭夹具与夹具擦拭侧朝下放置在试验表面上。立即启动飞机的运动。提起擦保持器时，将测试表面移动之后停止，并除去从所述保持器的擦拭。 </li></ol> 4.提取与分析<ol><li>提取和分析残留在PTFE转印基板任何RDX。 <ol><li>流速1mL甲醇中含在表面并进入2mL玻璃小瓶中的内标。使用同位素标记RDX作为内部标准。具有相似化学结构和物理性质的合适的类似物可以如果同位素标记的支架一起使用ARD不能获得。为RDX，附加上可接受的内标。将环四（HMX）。制备PTFE转印基板的方法，建议包裹纸环绕PTFE以最小化溶剂损失到纸张上。 </li><li>量化使用以前开发的分析协议解决方案。在此研究中使用的协议是基于电喷雾电离质谱（ESI-MS）。 </li></ol></li><li>提取和分析收集到的擦拭RDX。 <ol><li>切割擦拭材料下降到30毫米直径的圆形收集区域并放置一个2毫升的小玻璃瓶内的切口部。加入1毫升含内标甲醇。 </li><li>盖上小瓶和旋涡在10,000rpm下30秒。 </li><li>量化溶液尽可能迅速地防止被分析物和/或内部标准的再吸附到擦拭材料。提取尽可能的在一个小时内完成分析。 </li></ol></li><li>提取并分析关于PTFE的未使用的RDX粒子标准的一个子集相同的方式以得到基线起始质量为4.1。 </li><li>计算从PTFE基底转印效率（TE），以确定RDX的沉积在表面上的质量。 <img alt="式（1）" src="/files/ftp_upload/55484/55484eq1.jpg" /> 其中RDX 初始是提取的基线样品的平均附着量（步骤4.3）和RDX 保留 。是RDX的干转移（步骤4.1）之后剩余的PTFE基板上的质量。 </li><li>计算捕集效率（CE）的擦拭相对于所述表面上沉积的质量。 <img alt="公式2" src="/files/ftp_upload/55484/55484eq2.jpg" /> 其中RDX 擦拭距离擦拭（步骤4.2）中提取RDX的质量。 </li></ol> 5.质量控制<ol><li>进行最少重复3次。变异CE可以相对高，并且可能需要10次或更多的重复，以确定各采样因素的重要性。 <ol><li>清洁和再利用测试表面，用于重复如果空白测试表明清洁过程的功效。溶剂可能会影响表面纹理，以及任何需要使用它们的过程必须适用于所有的重复。 </li><li>使用新鲜的湿巾每个重复。 </li></ol></li><li>按照相同的程序，但用空白PTFE衬底测量过程空白。 </li></ol> 6.报告<ol><li>计算和报告TE为平均值和标准偏差和CE（n）的复制。 </li><li>报告1）类型的擦拭物，2）测试表面，3）的力，4）的速度，5）的行驶距离，6）温度，和7）湿度。 </li><li>报告中使用的类型和样品的细节。如果样品已制备比通过喷墨印刷，报告估计粒径和再现性等。 </li><li>报告任何其它因素，控制或观察到。 </li></ol>

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The authors have nothing to disclose. Certain commercial equipment, instruments, or materials are identified in this document. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose.

目前样品收集被视为限制步骤筛选的环境中提高检测能力。擦拭取样是需要测量和标准化，以评估当前的能力和支持新的采样材料和协议的发展。这里所描述的方法旨在提供这种测量的基础设施，以及控制大多数已知的因素是相关的擦拭取样。以前的工作已经表明，粒径，收集，测试表面，采样期间施加力擦拭，行驶距离是控制所有的重要因素。器乐方法允许用于在所施加的力的控制，擦拭的速度和行驶距离，并选择这些参数的值应落在预期在实际情况的范围内。该力是通过使用背衬重量在收集区域施加，并且应该小心，以实现均匀的力分布，以calc下乌拉特压力。 测试表面由用户选择，并应与实际筛查的环境中复制的采样挑战的预期范围内。采样擦拭物，以评估当前的实践和/或测量新设计的材料的效力选择。为了比较实验室之间的结果，同样的测试表面和擦拭物必须被使用，其可以通过指定关键参数或通过共享来自单个源购买的材料来完成。该ETD湿巾是市售的，但他们不断地在生产，不同批次可能有不同的属性。这些都是可以在将来通过实验室间的协调努力解决的问题。 用于评估收集效率的样品应与预计在实际生活中的物理特性。在爆炸物的情况下，我们已经制定了RDX的喷墨印刷解决方案来生产的方法微米大小的沉积物，能有效地转移到一个范围的底物和产生粒子沉积物尺寸范围从1至40微米。可替换地，可以使用固定大小的聚苯乙烯微球。吹打RDX溶液到特氟隆基板通常导致单存可能是相当大的，并转移到后表面的颗粒尺寸是未知的。这种方法可用于采样的研究，如果颗粒尺寸的特征，并显示出可重现的。 用于评估炸药采样效率描述的这种方法，但也可以应用于环保，核能，或法医学应用。的样品中，再次，应开发以匹配实际应用中，并且在颗粒的残基的情况下，相同类型的从聚四氟乙烯干式转印的是适当的。从比颗粒转移其它来源，例如从蒸汽冷凝，不同类型的样品所产生的表面污染可能更合适。 该技术的电流限制是不能改变的采样方向。当前的配置允许在一个单一的方向上的移动只，因此，对于通常发生在物体的领域采样方向变化无法控制。目前，我们正在解决这个需求通过将X - Y移动，并允许特定的抽样模式来填充区域。

筛选在机场和其他地点的爆炸物痕迹是在公众的反对恐怖主义威胁的保护中至关重要的一步。目前的做法主要侧重于表面污物擦拭取样从往货舱由人来处理项目，该人本身，和项目。收集擦巾使用通常基于收集的固体材料的热脱附商业炸药跟踪检测器（的ETD）立即分析的领域，与由离子迁移谱1或更最近，质谱检测。可用于样本采集和分析时间的总量是由需要尽量减少对旅客和货物吞吐量的影响有限。采样协议必须进行优化，以收集在最短的时间，这就要求标准化的测量，可衡量的因素擦拭收集重要最样品。 擦拭取样是用于在健康，环境和法规领域2，3，4，5，6，7取样表面污染的一般做法。典型的做法包括保持由手和采样使用一般的覆盖模式的固定区域内的擦拭。为了增加在擦拭因素，包括力和速度控制，我们开发了一种工具的方法来模拟擦拭采样8，其也被用于评估生物擦拭采样9效率。用于粘附测量的商业设备适应于目的;它包括下一个固定擦拭移动以固定的速度和距离的平坦表面。采样期间的力由设置在擦拭支架的顶部上的重量进行控制。感兴趣的表面（面料，PLASTICS，金属等 ）被放置在平坦表面上和颗粒样品放置在该表面上的固定区域。我们早期的工作中使用的聚苯乙烯胶乳微球作为试验粒子，粒径显示出具有对粒子收集的效果，具有小于（9微米）球收集更有效地大（42μm）的球体。我们还发现在收集效率有所改善，采样期间增加作用力，并观察在不同的表面收集和不同的抹布差异。 在随后的工作中，我们发现，聚苯乙烯颗粒可以通过继续收集后在表面擦拭，降低了表观收集效率10被再沉积。这是微量爆炸物探测的一个重要的考虑因素，在筛选的情况抽样商品，如手提箱，可相对于擦拭收集面积大，需要广泛的旅行DISTANCES覆盖项目的区域，甚至一个很小的比例。因此，样品收集后的表面上的行驶距离是一个重要因素，并且场协议通常定义之前每个分析所覆盖的最大容许距离。 微球的形状不像真正的炸药颗粒11，12和它们的化学和物理特性可以使他们爆炸物的不足模拟擦拭收集实验。为了解决这种限制，我们开发了含有炸药1,3,5- trinitroperhydro -1,3,5-三嗪（RDX）具有已知粒径的试验材料。该测试材料是通过在上基板特氟隆阵列的RDX溶液，与通过蒸发在所述阵列中的每个点处形成微米大小的固体沉积物的喷墨印刷纳升体积制成。所述沉积物通过摩擦在表面上转印到测试表面上，并且将所得部分ICLE大小由起始存款尺寸限定。所需的颗粒直径，如通过含有微量爆炸物指纹分析测定，为10至20μm。沉积物还可以通过吸取的溶液微升体积到特氟隆基板13形成的，但它们会干燥成一个单一的大型矿床，通常大得多的是颗粒尺寸的所希望的范围（相关与这个工作RDX质量）。喷墨RDX粒子标准在这项工作中使用定量提取和分析程序沿着演示用于确定擦拭收集效率的方法。这些测量旨在促进新采样的发展提供更好的收集效率湿巾，并支持在现场取样的最佳做法，包括靶向产生更多的样本，适当用力收集过程中使用的表面，以及该地区之前的分析覆盖。

<table><tbody><tr><td>Slip/Peel Tester</td><td>Imass</td><td>TL-2300</td><td>replaces TL-2200 used in protocol</td></tr><tr><td>3D printer</td><td>Stratasys</td><td>Connex500</td><td>VeroWhite resin as printing material</td></tr><tr><td>steel rod with thread</td><td>McMaster-Carr</td><td>7786T14</td><td>cut to size for desired weight, multiple online vendors available</td></tr><tr><td>felt or rubber</td><td></td><td></td><td>backing material in wipe holder, multiple online vendors available</td></tr><tr><td>PTFE substrate</td><td>SPI Supplies</td><td>01426-AB</td><td>1&quot; wide Bytac Bench and Shelf protector, Al-backed, cut to size</td></tr><tr><td>RDX solution</td><td>Cerilliant Analytical Reference Standards</td><td>ERR-001S</td><td>1,000 mg/mL in acetonitrile</td></tr><tr><td>Inkjet printer</td><td>MicroFab Technologies, Inc.</td><td>jetlab4 xl-B</td><td></td></tr><tr><td>Isotopically tagged RDX</td><td>Cambridge Isotope Laboratories</td><td>CLM-3846-S</td><td>For internal analytical standard</td></tr><tr><td>2 mL glass vial</td><td>Restek</td><td>21140 /24670</td><td></td></tr><tr><td>Methanol</td><td>Sigma Aldrich</td><td>14262</td><td>Chromasolv grade</td></tr><tr><td>ETD wipe 1</td><td>DSA Detection</td><td>DSW8055P</td><td>Ionscan 500 DT wipe</td></tr><tr><td>ETD wipe 2</td><td>DSA Detection</td><td>ST1318P</td><td>Itemiser DX wipe</td></tr><tr><td>Ballistic nylon fabric</td><td>Seattle Fabrics</td><td>1050 Denier Ballistics</td><td></td></tr><tr><td>Synthetic leather fabric</td><td></td><td></td><td>contact authors for sample</td></tr></tbody></table>

standardized method for measuring collection efficiency from wipe-sampling of trace explosives

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency are needed to evaluate and optimize sampling protocols. The approach described here is designed to provide this measurement infrastructure, and controls most of the factors known to be relevant to wipe-sampling. Three critical factors (the applied force, travel distance, and travel speed) are controlled using an automated device. Test surfaces are chosen based on similarity to the screening environment, and the wipes can be made from any material considered for use in wipe-sampling. Particle samples of the explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) are applied in a fixed location on the surface using a dry-transfer technique. The particle samples, recently developed to simulate residues made after handling explosives, are produced by inkjet printing of RDX solutions onto polytetrafluoroethylene (PTFE) substrates. Collection efficiency is measured by extracting collected explosive from the wipe, and then related to critical sampling factors and the selection of wipe material and test surface. These measurements are meant to guide the development of sampling protocols at screening venues, where speed and throughput are primary considerations.

这个协议的精确从各种各样的可能的测试表面测量收集效率的能力依赖于样本和它的限制，以在表面上的特定区域的物理特性。如果样品是所定义的区域之外，它可能无法完全擦除采样过程中遇到，并且收集效率将人为地降低。此外，如果颗粒与预期中的微量残留炸药实粒子显著不同，收集效率的测量可能不具有代表性。出于这些原因，我们建议使用这已被证明产生适当的粒度特性，并转移到一个限定的区域与协议一致的内表面测试样品的特定类型的。直接溶液沉积以形成颗粒取决于表面的质地和组合物，并且可以不导致representative样本。 结果在表1中给出对于给定的7.5N的力，并测试表面代表行李的（弹道尼龙机织织物）商业ETD擦拭物1（间位芳族聚酰胺聚合物），对于两个不同的行进距离。所有实验中的移动速度为50毫米/秒，和收集过程中的温度和相对湿度分别为20±2℃和40±4％RH，。结果表明，较长的路径长度导致降低的收集效率，预计由于颗粒10的再沉积。所述36厘米行驶距离，通过使用三个单独的道次表面上，起重在每个路径的端部的擦拭和平移表面以暴露出新鲜的采样路径来实现。延伸的行进距离的这种方法需要抹被提升并多次向下放置，并与连续的可产生不同的结果<html>样本路径。在筛选的方案，很可能是在擦拭被提升并在项目更换很多次，所以这种方法为延长行驶距离是合适的。 从PTFE基板的RDX沉积物的TE的高，如预期的该表面。因为转座因子是接近100％，并且有由基底（步骤3.2.3）的目视检查提供质量保证，TE的测量可以在不影响显著此测试面的CE结果被消除。其他测试表面可具有低或多个可变的TE。在CE的不确定性预期根据我们的经验，迄今这种技术的范围内。第二商业ETD擦拭（PTFE涂覆的编织的玻璃纤维）通常具有比间位芳族聚酰胺聚合物的不确定性擦拭下，尽管它也有在一般（ 图4）下的CE。我们以前用的聚苯乙烯微球工作<html>相比与擦拭物1 F"&gt; 8是具有用于ETD所观察到的低收集效率一致的擦拭2。 <img alt="图1" src="/files/ftp_upload/55484/55484fig1.jpg" /> 图1. 原理图擦拭采样装置（左和中间）与模板测试表面（右）上的样品放置。擦拭收集区域，30毫米直径的圆，的覆盖区被示出在采样路径的开始和结束。擦巾放置在测试表面上，直接行进通过样本位置（一般为5毫米×5mm或更小），并在表面上结束。的行驶距离是从C，所述样品的位置，到最后。 <a href="http://ecsource.jove.com/files/ftp_upload/55484/55484fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> PLOAD / 55484 / 55484fig2.jpg" /&gt; 图2. 示例擦拭支架。自定义保持器组成部件示于左上角的，并且包括三维打印产生的两个塑料部件。这两个组件用来夹住的地方擦拭，并通过两个翼形螺丝固定在一起。可附接的不锈钢砝码是实心杆，在其一端附接至保持器的螺纹螺柱。吊环螺栓是用于约束线的附接。 <img alt="图3" src="/files/ftp_upload/55484/55484fig3.jpg" /> 图3. 设备的配置。黄色纸模板由通过10cm至适合10cm的正方形钢测试的表面上，用于采样路径的切口。与模板中的表面被放置在可移动的平面和调整，直到约束线被拉紧并居中于采样路径。该模板用于配置日È设备和传送测试样品时，但不到位时擦拭采样。 <a href="http://ecsource.jove.com/files/ftp_upload/55484/55484fig3large.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/55484/55484fig4.jpg" /> 图4. 结果合成皮革试验表面和36厘米行驶距离，通过使用3次的每组12厘米，对于两个不同的擦拭物实现。在CE不确定性给定为1个标准差。 <table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td> 行驶距离（cm） </td><td> 力（N） </td><td> TE（％） </td><td> RSD（％） </td><td> CE（％） </td><td> RSD（％） </td><td> ñ </td></tR&gt; <tr><td> 36 * </td><td> 7.5 </td><td> 97.4±2.1 </td><td> 2.2 </td><td> 11.7±4.0 </td><td> 34.0 </td><td> 9 </td></tr><tr><td> 12 </td><td> 7.5 </td><td> 98.5±1.3 </td><td> 1.3 </td><td> 22.6±3.4 </td><td> 15.2 </td><td> 4 </td></tr><tr><td colspan="7"> *的每个12厘米3遍。 </td></tr></tbody></table> 表1 的结果为商业ETD擦拭物1个编织尼龙织物测试表面为两个不同的行进距离。在TE和CE不确定性给定为1个标准差。

Watch this Scientific Journal Video about Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives at JoVE.com

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

Optimized sampling protocols and the development of new wipe materials can be facilitated by standardized measurements of collection efficiency from wipe-sampling. Our approach for sampling trace explosives uses an automated device to control speed, force, and distance during wipe-sampling followed by extraction of collected explosives.

从微量炸药的擦拭取样测量收集效率的标准化方法

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common ...

standardized-method-for-measuring-collection-efficiency-from-wipe

Research

JoVE Journal

Engineering

9.5K 次观看.  National Institute of Standards and Technology. Optimized sampling protocols and the development of new wipe materials can be facilitated by standardized measurements of collection efficiency from wipe-sampling. Our approach for sampling trace explosives uses an automated device to control speed, force, and distance during wipe-sampling followed by extraction of collected explosives.

视频: Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

Physical, Chemical and Biological Characterization of Six Biochars Produced for the Remediation of Contaminated Sites

The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with specific functions (e.g. carbon sequestration, soil quality improvements, or contaminant sorption). In 2013, the International Biochar Initiative (IBI) made publically available their Standardized Product Definition and Product Testing Guidelines (Version 1.1) which set standards for physical and chemical characteristics for biochar. Six biochars made from three different feedstocks and at two temperatures were analyzed for characteristics related to their use as a soil amendment. The protocol describes analyses of the feedstocks and biochars and includes: cation exchange capacity (CEC), specific surface area (SSA), organic carbon (OC) and moisture percentage, pH, particle size distribution, and proximate and ultimate analysis. Also described in the protocol are the analyses of the feedstocks and biochars for contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and mercury as well as nutrients (phosphorous, nitrite and nitrate and ammonium as nitrogen). The protocol also includes the biological testing procedures, earthworm avoidance and germination assays. Based on the quality assurance / quality control (QA/QC) results of blanks, duplicates, standards and reference materials, all methods were determined adequate for use with biochar and feedstock materials. All biochars and feedstocks were well within the criterion set by the IBI and there were little differences among biochars, except in the case of the biochar produced from construction waste materials. This biochar (referred to as Old biochar) was determined to have elevated levels of arsenic, chromium, copper, and lead, and failed the earthworm avoidance and germination assays. Based on these results, Old biochar would not be appropriate for use as a soil amendment for carbon sequestration, substrate quality improvements or remediation.

Biochar is a carbon-rich material used as a soil amendment with the ability to sustainably sequester carbon, improve substrate quality and sorb contaminants. This protocol describes the 17 analytical methods used for the characterization of biochar, which is required prior to large scale implementation of these amendments in the environment.

物理，化学和六Biochars生产的生物表征污染场地修复的

The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with ...

科研

环境科学

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

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

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

定量检测痕量爆炸物蒸气通过程序升温脱附 - 气相色谱 - 电子捕获检测器

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

化学

A Simple Method for Automated Solid Phase Extraction of Water Samples for Immunological Analysis of Small Pollutants

A new method for solid phase extraction (SPE) of environmental water samples is proposed. The developed prototype is cost-efficient and user friendly, and enables to perform rapid, automated and simple SPE. The pre-concentrated solution is compatible with analysis by immunoassay, with a low organic solvent content. A method is described for the extraction and pre-concentration of natural hormone 17&#946;-estradiol in 100 ml water samples. Reverse phase SPE is performed with octadecyl-silica sorbent and elution is done with 200 &#181;l of methanol 50% v/v. Eluent is diluted by adding di-water to lower the amount of methanol. After preparing manually the SPE column, the overall procedure is performed automatically within 1 hr. At the end of the process, estradiol concentration is measured by using a commercial enzyme-linked immune-sorbent assay (ELISA). 100-fold pre-concentration is achieved and the methanol content in only 10% v/v. Full recoveries of the molecule are achieved with 1 ng/L spiked de-ionized and synthetic sea water samples.

A protocol for the extraction and pre-concentration of estradiol from water samples by using an automated and miniaturized system is presented.

对水样的自动固相萃取小污染物的免疫学分析的简单方法

A new method for solid phase extraction (SPE) of environmental water samples is proposed. The developed prototype is cost-efficient and user friendly, and ...

Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies

Most of the trace metal concentrations in ambient waters obtained a few decades ago have been considered unreliable owing to the lack of contamination control. Developments of some techniques aiming to reduce trace metal contamination in the last couple of decades have resulted in concentrations reported now being orders of magnitude lower than those in the past. These low concentrations often necessitate preconcentration of water samples prior to instrumental analysis of samples. Since contamination can appear in all phases of trace metal analyses, including sample collection (and during preparation of sampling containers), storage and handling, pretreatments, and instrumental analysis, specific care needs to be taken in order to reduce contamination levels at all steps. The effort to develop and utilize "clean techniques" in trace metal studies allows scientists to investigate trace metal distributions and chemical and biological behavior in greater details. This advancement also provides the required accuracy and precision of trace metal data allowing for environmental conditions to be related to trace metal concentrations in aquatic environments.
This protocol that is presented here details needed materials for sample preparation, sample collection, sample pretreatment including preconcentration, and instrumental analysis. By reducing contamination throughout all phases mentioned above for trace metal analysis, much lower detection limits and thus accuracy can be achieved. The effectiveness of "clean techniques" is further demonstrated using low field blanks and good recoveries for standard reference material. The data quality that can be obtained thus enables the assessment of trace metal distributions and their relationships to environmental parameters.

Special care using "clean techniques" is required to properly collect and process water samples for trace metal studies in aquatic environments. A protocol for sampling, processing, and analytical procedures with the aim of obtaining reliable environmental monitoring data and results with high sensitivity for detailed trace metal studies is presented.

清洁取样和痕量金属研究河和河口水域分析

Most of the trace metal concentrations in ambient waters obtained a few decades ago have been considered unreliable owing to the lack of contamination ...

Protocols for Quantifying Transferable Pesticide Residues in Turfgrass Systems

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes onto humans. For this reason, transferable pesticide residue experiments are required for registration and re-registration by the United States Environmental Protection Agency (USEPA). Although such experiments are required, limited specificity is required pertaining to experimental approach. Experimental approaches used to assess pesticide transfer to humans including hand wiping with cotton gloves, modified California roller (moving a roller of known mass over cotton cloth) and soccer ball roll (ball wrapped with sorbent strip) over three treated turfgrass species (creeping bentgrass, hybrid bermudagrass and tall fescue maintained at 0.4, 5 and 9 cm, respectively) are presented. The modified California roller is the most extensively utilized approach to date, and is best suited for use at low mowing heights due to its reproducibility and large sampling area. The soccer ball roll is a less aggressive transfer approach; however, it mimics a very common occurrence in the most popular international sport, and has many implications for nondietary pesticide exposure from hand-to-mouth contact. Additionally, this approach may be adjusted for other athletic activities with limited modification. Hand wiping is the best approach to transfer pesticides at higher mowing heights, as roller-based approaches can lay blades over; however, it is more subjective due to more variable sampling pressure. Utility of these methods across turfgrass species is presented, and additional considerations to conduct transferable pesticide residue research in turfgrass systems are discussed.

Transferable pesticide residue experiments in turfgrass systems are integral components of human risk exposure assessments. Experimental approaches to measure transferable residues should be adjusted to the human interaction of interest and turfgrass system dynamics. Three transferable pesticide residue protocols are presented and the suitability across three turfgrass systems is discussed.

协议在草坪系统量化转换农药残留

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes ...

Blast Quantification Using Hopkinson Pressure Bars

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils.

This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

高炉利用定量霍普金森杆

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures ...

工程学

Failure of Cleaning Verification in Pharmaceutical Industry Due to Uncleanliness of Stainless Steel Surface

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A series of factors were assessed, including drug product spike levels, spiking procedure, drug-excipient ratios, analyst-to-analyst variability, intraday variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned the coupon surface was identified as the major contributor to low and variable recoveries. Assessment of cleaning the surface of the coupons with clean-in-place solutions (CIP) gave high recovery (&#62;90%) and reproducible results (Srel&#8804;4%) regardless of the conditions that were assessed previously. The approach was successfully applied for cleaning verification of small molecules (MW &#60;1,000 Da) as well as large biomolecules (MW up to 50,000 Da).

The lack of a well-defined procedure that consistently cleaned coupon surfaces was identified as the major contributor to low and variable recoveries in cleaning verification. This manuscript describes the correct protocol of cleaning stainless steel coupons.

清洁验证在不锈钢表面脏制药行业中的失败

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A ...

Identifying Per- and Polyfluorinated Chemical Species with a Combined Targeted and Non-Targeted-Screening High-Resolution Mass Spectrometry Workflow

Historical and emerging per- and polyfluoroalkyl substances (PFASs) have garnered significant interest from the public and government agencies from the local to federal levels. The continuing evolution of PFAS chemistries presents a challenge to the environmental monitoring, where ongoing development of targeted methods necessarily lags the discovery of new chemical compounds. There is a need, therefore, to have forward-looking methodologies that can detect emerging and unexpected compounds, monitor these species over time, and resolve details of their chemical structure to enable future work in human health. To this end, non-targeted analysis by high-resolution mass spectrometry offers a broad base detection approach that can be combined with almost any sample preparation scheme and provides significant capabilities for compound identification after detection. Herein, we describe a solid-phase extraction (SPE) based sample concentration method tuned for shorter chain and more hydrophilic PFAS chemistries, such as per fluorinated ether acids and sulfonates, and describe analysis of samples prepared in this fashion in both targeted and non-targeted modes. Targeted methods provide superior quantification when reference standards are available but are intrinsically limited to expected compounds when performing analysis. In contrast, a non-targeted approach can identify the presence of unexpected compounds and provide some information about their chemical structure. Information about chemical features can be used to correlate compounds across sample locations and track abundance and occurrence over time.

Here, we present a protocol for the sequential targeted quantification and non-targeted analysis of fluorinated compounds in water by mass spectrometry. This methodology provides quantitative levels of known fluorochemical compounds and identifies unknown chemicals in related samples with semi-quantitative estimates of their abundance.

利用目标筛选和非靶向筛选高分辨率质谱相结合的工作流程识别跨氟和多氟化学物种

Historical and emerging per- and polyfluoroalkyl substances (PFASs) have garnered significant interest from the public and government agencies from the ...

Quantification and Size-profiling of Extracellular Vesicles Using Tunable Resistive Pulse Sensing

Extracellular vesicles (EVs), including &#8216;microvesicles&#8217; and &#8216;exosomes&#8217;, are highly abundant in bodily fluids. Recent years have witnessed a tremendous increase in interest in EVs. EVs have been shown to play important roles in various physiological and pathological processes, including coagulation, immune responses, and cancer. In addition, EVs have potential as therapeutic agents, for instance as drug delivery vehicles or as regenerative medicine. Because of their small size (50 to 1,000 nm) accurate quantification and size profiling of EVs is technically challenging.
This protocol describes how tunable resistive pulse sensing (tRPS) technology, using the qNano system, can be used to determine the concentration and size of EVs. The method, which relies on the detection of EVs upon their transfer through a nano sized pore, is relatively fast, suffices the use of small sample volumes and does not require the purification and concentration of EVs. Next to the regular operation protocol an alternative approach is described using samples spiked with polystyrene beads of known size and concentration. This real-time calibration technique can be used to overcome technical hurdles encountered when measuring EVs directly in biological fluids.

Extracellular vesicles play important roles in physiological and pathological processes, including coagulation, immune responses, and cancer or as potential therapeutic agents in drug delivery or regenerative medicine. This protocol presents methods for the quantification and size characterization of isolated and non-isolated extracellular vesicles in various fluids using tunable resistive pulse sensing.

定量和大小分析外囊泡的使用可调电阻脉冲检测

Extracellular vesicles (EVs), including &#8216;microvesicles&#8217; and &#8216;exosomes&#8217;, are highly abundant in bodily fluids. Recent years have ...

生物工程

Optimization of Radiochemical Reactions using Droplet Arrays

Current automated radiosynthesizers are designed to produce large clinical batches of radiopharmaceuticals. They are not well suited for reaction optimization or novel radiopharmaceutical development since each data point involves significant reagent consumption, and contamination of the apparatus requires time for radioactive decay before the next use. To address these limitations, a platform for performing arrays of miniature droplet-based reactions in parallel, each confined within a surface-tension trap on a patterned polytetrafluoroethylene-coated silicon "chip", was developed. These chips enable rapid and convenient studies of reaction parameters including reagent concentrations, reaction solvent, reaction temperature and time. This platform permits the completion of hundreds of reactions in a few days with minimal reagent consumption, instead of taking months using a conventional radiosynthesizer.

This method describes the use of a novel high-throughput methodology, based on droplet chemical reactions, for the rapid and economical optimization of radiopharmaceuticals using nanomole amounts of reagents.