Name: extraction and characterization of surfactants from atmospheric aerosols
Uploaded: 2017-04-21T13:00:00.000+00:00
Duration: 9 min 34 s
Description: Watch this Scientific Journal Video about Extraction and Characterization of Surfactants from Atmospheric Aerosols at JoVE.com

这项工作是由SONATA，法国法新社国立德拉RECHERCHE（ANR-13-IS08-0001）和美国国家科学基金会的合作项目资助。克里斯廷·巴杜埃尔是由法国国家研究署（ANR）通过ANR-16 ACHN-0026项目资助。作者还热烈地感谢马里哈·玛格斯，安娜Cvitešić，桑哈·弗卡·米洛萨弗赫维奇和伊雷娜Ciglenecki，从萨格勒布的鲁道赫尔·博斯科维奇研究所，克罗地亚与滨海Frapa，罗戈兹尼察，克罗地亚气溶胶采样的帮助。

1.准备协议的材料如表1所列<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td> 材料 </td><td> 准备/清洗 </td></tr><tr><td> 消耗品 （塑料注射器，针头，4毫升小瓶，巴斯德移液管，微量提示） </td><td>要直接使用，无需预处理和使用后丢弃。 </td></tr><tr><td rowspan="7"> 可重复使用的玻璃器皿 （烧杯（超纯水）; 15，30，和60个毫升瓶的软木塞;管用于固相萃取（SPE）;以及磁力搅拌棒） </td><td>用乙醇洗（只对于用于比色法的小瓶）。 </td></tr><tr><td>依次漂洗用自来水，乙醇，自来水，超纯水。 </td></tr><tr><td>填充玻璃小瓶和含有烧杯中的软木塞，磁搅拌器，和SPE TUBES用超纯水，并放置在超声波浴15分钟。 </td></tr><tr><td>除去水分，同时用超纯水冲洗。 </td></tr><tr><td>干在室温下在空气中的玻璃器皿。 </td></tr><tr><td>一旦干燥，关闭所有的瓶子并将它们存储的掩护下，以避免灰尘收集。 </td></tr><tr><td>为了避免污染，使用不同的玻璃器皿的水提取和比色法。 </td></tr><tr><td rowspan="2"> 镊子和剪刀 </td><td>用乙醇和超纯然后用水冲洗。 </td></tr><tr><td>干燥的压缩空气。 </td></tr><tr><td rowspan="4"> 玻璃培养皿的盖子 </td><td>用自来水和刷子洗，然后用乙醇。 </td></tr><tr><td>用自来水，然后超纯水冲洗。 </td></tr><tr><td>干燥在室温下的空气。 </td></tr><tr><td>一旦干燥，关闭箱和STORË他们的掩护下，以避免灰尘收集。 </td></tr><tr><td rowspan="2"> SPE真空歧管 </td><td>用乙醇和超纯然后用水冲洗。 </td></tr><tr><td>干燥的压缩空气。 </td></tr><tr><td rowspan="2"> 石英比色皿（用于UV-Vis分析） </td><td>用乙醇洗涤，并用自来水，然后超纯水冲洗。 </td></tr><tr><td>干燥的压缩空气。 </td></tr></tbody></table> 表1:用于协议，包括它们的制备和清洗材料和玻璃器皿的列表。 2.气溶胶样品的处理注意:这里介绍的提取方法具有用于收集在至少8微克的总重量的石英纤维过滤器大气气溶胶样品被开发出来。在大气中的过滤器采集的气溶胶样品的方法不会在这里，但众多解释描述可以在文献中找到，如参考文献2，3，4，5，6个只有下列步骤以下划线表示。 <ol><li>数每个单独的过滤器。 注:在整个协议中的过滤器应该用干净的镊子进行操作，并通过他们的边举行。 </li><li>预条件通过在773ķ烘烤它们6小时的过滤器和铝箔或玻璃培养皿采样前。 </li><li>预称重，控制的温度和湿度条件下，使用具有至少1微克精度的微量天平，过滤器，以确定样品的预重量。 </li><li>定期取空白样品在开始时，过程中和在所述采样周期结束时，通过将过滤器上的采样器的过滤器保持器，但保持所述泵关闭相同的持续时间，作为实际的样品收集（ <e米&gt;例如。如果样本收集持续24个小时，空白滤器应留在采样器，与所述泵关闭，24小时）。用相同的协议作为用于实际样品分析这些空白。 </li><li>尽快取样后，包在容器（备份铝箔或玻璃陪替氏培养皿）的过滤器和在-18℃（255 K），直到分析在冰箱中存储它们。 </li><li>离开过滤器在干燥器称重之前平衡24个小时。确定通过取样后称重每个样品体积（在过滤器上收集的气溶胶质量）（和减去预采样重量）作为在预称重在相同的控制温度和相对湿度下。 </li></ol>从气溶胶样品表面活性剂3提取<ol><li> 水萃取 <ol><li>浸入超纯水中的过滤器样品2小时，在279±1 K的玻璃培养皿，盖上盖子并摇动培养皿而将它们保持平坦，关于电子非常30分钟。 注:47毫米过滤器浸渍在7毫升和150毫米的人的35ml。 120个毫米的玻璃培养皿，150mm的过滤器需要在四件与清洁剪刀要被切割之前被放置在培养皿中。 </li><li>用3×1毫升的超纯水清洗的注射器过滤器（0.40微米PVDF）。 </li><li>过滤器与所述清洁注射器过滤器在步骤3.1.1中获得的溶液，并将其放置在预称重60毫升玻璃瓶中。冲洗培养皿用5ml超纯水，用针筒式过滤器过滤水并将其添加到在60毫升玻璃瓶中的溶液。然后加权含有溶液以确定过滤的水的体积，并且在步骤4.4.5表面活性剂浓度的60毫升玻璃瓶中。 </li></ol></li><li> SPE（固相萃取）萃取 <ol><li>附加SPE二氧化硅基C18柱（参见材料列表有关墨盒的信息）到SPE真空歧管，其本身连接到泵。 </li><li>由流6毫升乙腈中与在1mL / min的流速并施加与所述泵的真空洗墨盒。用6mL的超纯水的重复。停泵足以维持水位高，将筒湿润。 </li><li>在小于1毫升/分钟的速率流过SPE柱在步骤3.1.3中获得的样品。 </li><li>流速1mL超纯水虽然盒用于清洁和通过施加在SPE建立更强的真空干燥的墨盒。 </li><li>洗脱通过以小于1毫升/分钟的流速流动4毫升通过它乙腈吸附在柱中的表面活性剂组分。 <ol><li>蒸发用的N 2通量所获得的乙腈溶液，得到干燥的表面活性剂提取物和超纯水的60μL重新溶解干燥提取物。 注意:从该方法得到的60种微升提取物然后可以用作表面活性剂的各种表征母体溶液。 </li></ol></li></ol></li><li> 提取效率的测定 注:对不同类型的表面活性剂的需要为他们的绝对浓度的在第4节为此，确定待确定的提取方法的效率，下面的协议需要施加到参考表面活性剂如，例如，十二烷基硫酸钠（SDS），二辛基磺基琥珀酸钠（AOT），二甲基benzyltetradecyl（zephiramine），氯化十六烷基三甲基氯化铵（CTAC），（1,1,3,3-四甲基丁基）苯基 - 聚乙二醇（参见材料列表），聚乙二醇十二烷基醚（见材料列表），枯草，鼠李糖脂，或L-α磷脂酰胆碱。 <ol><li>尖峰参考含水标准溶液（在1ml超纯水中10 -9〜10 -4摩尔的表面活性剂），进入干净的石英滤波器（克0.85克-2）用微量。平行地，添加这些溶液D的相同量irectly小瓶"初始解决方案"。 </li><li>干燥在24个小时的干燥器的过滤器（放置在培养皿中），并根据在第3.1-3.2协议与表面活性剂提取过滤器。 </li><li>测量参考化合物的浓度在初始与在第4节的提取效率描述的方法（参考文献在小瓶从步骤3.3.1溶液）和萃取溶液（从步骤3.3.2）被确定为论文的比率浓度。 注意:典型地，在这项工作中，SDS和AOT（阴离子表面活性剂），这种效率被发现是65±10％，对于zephiramine和CTAC（阳离子表面活性剂），它是20±5％，而对于（1,1 ，3,3-四甲基丁基）苯基 - 聚乙二醇（参见材料列表），聚乙二醇十二烷基醚（参见材料列表），枯草，鼠李糖脂，和L-α磷脂酰胆碱（非离子型表面活性剂）是90±10％。 </li></ol></li><li> Extracti上的样品中总表面活性剂的分数 注意:为了验证所提出的提取方法去除存在的所有分析的样品（ 即，所有其降低表面张力的化合物）在表面活性剂，可以进行下面的试验。 <ol><li>测量表面张力（见第5章）所述第一提取（步骤3.1.3）后参考化合物（或一个样品提取物）的一种已知的解决方案。它应该是大约50 MN M-1。 </li><li>测量所述第二提取步骤后剩下的溶液的表面张力，通过SPE柱传递步骤3.2.3之后即收集。此值应接近72.8±1 MN M -1，纯水的一个，显示出大部分或全部存在于样品中的表面活性化合物已被萃取除去。 </li></ol></li></ol> 4.表面活性剂的测定气溶胶相浓度的注意:的比色技术已被选择用于确定气溶胶相表面活性剂浓度的，它提供了绝对浓度，并且具有用于环境样品中的表面活性剂适当的灵敏度。 11，12，13，14，但它需要分别测量阴离子，阳离子和非离子表面活性剂的浓度，因为不同的试剂，必须使用对于每个表面活性剂类型。以下协议的所有解决方案必须以微量的准确性来制备，所有的反应必须在玻璃小瓶中进行。 <ol><li> 阴离子表面活性剂的比色滴定 <ol><li>在pH制备乙酸盐缓冲液中的溶液在水= 5（醋酸钠溶液0.2 M /乙酸溶液0.2M，在70/30体积计）的至少n 200μL，其中n是样本是数量的体积分析。 </li> &lt;LI&gt;准备EDTA的0.1M的溶液与至少NX 100μL，其中n是要被分析的样本的数目的体积。 </li><li>制备硫酸钠的1M的在水中的溶液与至少NX 500μL，其中n是要被分析的样本的数目的体积。 </li><li>制备乙基紫的在水中的溶液（C 31 H 42 N 3）11，15，16，170.49克L -1与至少NX 200μL，其中n是要被分析的样本的数目的体积。 </li><li>如果从第3节中所得到的60μL样品提取物开始，在60毫升玻璃瓶用盖使用微量稀释它们至10ml，用超纯水。否则，取10毫升样品，并添加醋酸缓冲液200微升，100μL的EDTA溶液，500μL的硫酸钠溶液和200中的乙基的μL使用微量紫溶液。 </li><li>添加2.5毫升甲苯于用微量，磁搅拌棒的溶液中，并搅拌以500rpm 1个小时。 </li><li>离开水和有机相至约10分钟设定。一旦它们被分离，除去甲苯相（上层相）用巴斯德玻璃吸管来执行UV-Vis分析（见4.4节）。 </li></ol></li><li> 阳离子表面活性剂的比色滴定 <ol><li>在pH制备乙酸盐缓冲液中的溶液在水= 5（醋酸钠溶液0.2 M /乙酸溶液0.2M，在70/30体积计）的量至少为nx 1毫升，其中n是样本是数量分析。 </li><li>制备disulfine蓝色的溶液（C 27 H 32 N 2 O 6 S 2）11，18以2.58克L -1在90:10的水/乙醇混合物（具有的水的体积第一稀释染料，然后加入v的乙醇olume）中，用至少为nx 500μL，其中n是要被分析的样本的数目的体积。 </li><li>放置10毫升样品的在30毫升玻璃瓶中的盖，并添加1毫升的醋酸盐缓冲液，并使用微量移液管的disulfine蓝色溶液的500μL。 </li><li>添加2.5毫升氯仿用微量，磁力搅拌棒，并搅拌在500rpm下1个小时。 </li><li>离开水相和有机相分离约10分钟，用注射器除去氯仿（下层相）来执行UV-Vis分析后（见4.4节）。 </li></ol></li><li> 非离子表面活性剂的比色滴定 注意:对于非离子表面活性剂的滴定，这是不可能的，以确定染料的所有非离子表面活性剂进行反应，但硫氰酸钴（钴（NCS）2）被选为其与化合物的最广泛的反应。 12，19 <ol><li>准备通过混合NX6.2克硫氰酸铵和NX2.8克硝酸钴六水合物在NX 10毫升水中，其中n是要被分析的样本的数目硫氰酸钴的溶液。 </li><li>放置3 mL的样品在15毫升玻璃瓶中的盖，并添加用微量的硫氰酸钴溶液1毫升。 </li><li>用微量，磁力搅拌棒，并搅拌加入2毫升氯仿中1个小时，以500rpm </li><li>离开水相和有机相后分离约10分钟，除去氯仿（下层相），使用注射器进行UV-Vis吸收分析（见4.4节）。 </li></ol></li><li> 校准曲线和定量通过UV-Vis光谱 <ol><li>通过在系列的参考化合物的已知的解决方案，如SDS或AOT中的612处测量的吸光度建立阴离子表面活性剂的校正曲线（吸光度VS浓度曲线）。 注:通常12个解决方案浓度0和5μM（和包括一些重复）之间应当用于建立曲线。 一个独特的校准曲线应与阴离子化合物（SDS和AOT），用ε斜率= 0.37±0.02μM-1和0.054微米的检测限，对于所有的阴离子表面活性剂来获得。 </li><li>通过类似的方法建立阳离子表面活性剂的校正曲线，但测量吸光度在628 nm和使用诸如Zephiramine或CTAC参考化合物。 注:斜率应ε= 0.35±0.05μM-1，检测限0.059μM，对于所有的阳离子表面活性剂。 </li><li>通过类似的方法建立的非离子表面活性剂的校正曲线，但对于一个范围为0至20μM的浓度，测量的吸光度在317nm处，并使用聚乙二醇十二烷基醚（参见材料列表）作为参考化合物。 </li><li>为了确定表面活性剂的染料的浓度复合在部分4.1，4.2和4.3所得到的有机溶液，地方〜1.5-2毫升在1cm石英池这些溶液中，并在612，628和317nm处，测量其吸光度分别用紫外可见分光光度计。在此之前的各溶液的测量，取有机溶剂（对于阴离子表面活性剂的方法和氯仿为阳离子和非离子表面活性剂的方法甲苯）空白 注意:与对阴离子和阳离子表面活性剂，使用硫氰酸钴作为染料将给予不同的非离子表面活性剂不同的校准曲线。使用聚乙二醇十二烷基醚，如这里建议，将低估大多数非离子表面活性剂的浓度，从而确保对测量的误差总是相同的符号， 即低估实际浓度。的使用斜坡聚乙二醇十二烷基醚作为参考应该给的ε斜率= 0.013±0.001μM-1和0.3μm的检测限。 注意:基于不同的校准斜坡与不同的非离子表面活性剂和我们估计6上的非离子表面活性剂浓度的系统性低估用这种方法，以约为系数的事实，一些表面活性剂可能不会在所有由硫氰酸钴检测得到2，这是不确定性的在表面活性剂浓度的总的最大来源。 </li><li>确定每个样品的阴离子，阳离子的浓度的总和的总表面活性剂浓度，以及非离子表面活性剂单独计量6和从步骤3.1.3由所提取的体积效率校正每个浓缩后，并通过在所确定的各自的提取效率步骤3.3。 注意:这些总浓度在总的不确定性，估计到33％，因为在非离子型表面活性剂浓度的不确定性的居多。 </li><li>确定平均表面活性剂concen气溶胶样品中trations通过气溶胶样品体积的提取物体积（60μL）的比值为所述提取物中获得的浓度乘以。 </li></ol></li></ol> 5.测定水中的表面活性剂的绝对表面张力曲线<ol><li> 表面张力测量通过悬滴张力测量 注:对于气溶胶样品，表面张力的测量最好用悬滴方法制成的，因为这是一个需要的最小样品体积的方法（关于该张力的详细信息，参见材料列表 ）。虽然这样的测量是在1.4和2.4毫米的直径的微滴进行的实验表明，测得的表面张力是相同的含有相同浓度的表面活性剂的微米尺寸的液滴的。 10，20在整个测量，温度必须是恒定的，以至少0;±3 K，和液滴体积应进行连续监测，以排除蒸发的效果。每个液滴必须留给平衡（表面张力值并不改变任何更多）之前进行测量和每个测量应重复3〜5次。 <ol><li>启动张力相机和软件（见材料清单参考）。通过测量超纯水的液滴的表面张力，在以下步骤的协议5.1.2-5.1.5下面校准张力。 </li><li>填充1mL注射器用Ø0.30毫米针（对于σ&lt;45 MN m -1）个或一个Ø0.51毫米（对于σ&gt;为45mN m -1）个针与在步骤3.2.6并将其放置所得到的表面活性剂溶液在张力，确保针尖在相机领域。 </li><li>通过推动活塞产生直径在针的尖端1和3毫米之间的微滴。 </li><li>拍照或液滴的视频将其与日之前下降E软件。 </li><li>运行软件的分析功能，以适应小滴形状的Young-Laplace方程，并得到表面张力值。甲上面指出的，该操作应重复数次相同的液滴，直到表面张力不发生变化的任何更多，以确保该表面活性剂已经达到在液滴平衡。 注意:在这些表面张力测量的不确定性整体通常是±（0.3-1.0）MN米-1。 </li></ol></li><li> 完整的表面张力曲线和CMC <ol><li>测量初始提取物的表面张力，在步骤3.2.6获得的，以下在5.1的协议。 </li><li>测量在相同的提取物的总表面活性剂浓度，以下在第4节这此萃取液浓缩和表面张力将提供曲线的起始点的协议。 </li><li>绘制曲线的剩余部分，按广告由2倍稀释提取物丁超纯水用微量。测量稀释的溶液的表面张力。 </li><li>重复步骤5.2.2直到溶液达到（或接近）的纯水（72.8±1 MN米-1）的表面张力。对于每个这些稀释的溶液的表面张力值和稀释因子将提供限定的表面张力曲线的点。 </li><li>通过将提取物的样品体积的比率在提取物中的浓度乘以确定初始气溶胶样品中的表面活性剂的平均浓度。 注意:作为气溶胶样品体积通常比60μL提取物时，该气溶胶表面活性剂浓度通常比提取物的浓度，从而在曲线的x轴的最远点大。 </li><li>积的表面张力曲线（ 图2）。对于此，将对应于在气溶胶中的条件（x轴=表面活性剂concentrati第一点在步骤5.2.5确定的气溶胶样品中; y轴=在步骤5.2.1在60μL提取物溶液测得的最小表面张力）。然后将对应于步骤5.2.1（在60微升提取x轴=表面活性剂浓度; y-轴=最小表面在60μL提取物溶液测得的张力）的60微升提取物中的第二个点。然后将对应于在稀释的提取物溶液中的120μL步骤5.2.2（x轴=表面活性剂浓度的稀释气溶胶提取物中的第三点=浓度在60μL提取液以2的因子分; y-轴:最小表面张力在120μL提取物溶液测得），依此类推，直到最后测量的表面张力（步骤5.2.3） </li><li>一旦表面张力曲线建立，可以确定CMC图形通过确定陡坡和最小表面张力水平之间的交叉点（ 见图2）。 注意:只有在日提取物中的ë表面活性剂浓度是显著高于CMC（曲线上的尖锐过渡以上）CMC的值和最小的表面张力的能准确地被确定。但是，如果该浓度低于CMC下，CMC的确切值不能被确定，并且该提取物的表面张力只会给所述样品中的所述一个的上限。 </li></ol></li></ol>

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作者什么都没有透露。

在该协议中，所有关键步骤已经详细说明。它们包括气溶胶的过滤器上收集，从它们的表面活性剂的提取（使用双提取:水提取后跟一个SPE提取）和提取物（表面张力和浓度测量）的分析。 对于整个方法，质量控制已经通过在空白滤波器（提取和分析方法的应用由1）偏差&lt;5 MN米-1，上下的检测极限表面张力和吸光度比色超纯水相比方法）; 2）通过确定浓度的给定范围中的提取效率和它们的不确定性，包括再现性/重复性，提取表面活性剂的重量％，3）通过检查比色法的潜在干扰，通过检查该方法检测，即仅靶向型表面活性剂（anioNIC，阳离子型和非离子型）和没有看到别人如参考文献4充分详细，6）通过检查从气溶胶提取物上比色法如参照图6详尽地说明潜在干扰物（无机盐，小氨基酸）。 据我们所知，从这篇文章中提出的大气样本的表面活性剂的提取方法是目前大气化学最有选择性的。特别地，它是比过去用于这些化合物的调查进行的简单的水萃取得多的选择性。 11，23，24的第二个提取步骤是重要的，因为它已被证明以除去离子成分，例如无机盐和小的有机酸，是在高浓度的气溶胶样品中，并与浓度测量电干扰对此语句。 6本提取方法也已经显示，以除去存在的所有样品中的表面活性剂，在表面上和在本体。由此所得到的萃取物浓缩，足以允许对这些化合物的精确刻划。 但是，除了表面活性剂，可能的是，从大气气溶胶提取的其他非极性或轻微极性化合物。例如，"腐植酸样物质"（HULIS），即通常是由类似的方法25和，根据采样区域中提取，可以存在于提取物中。这些化合物仅轻度的表面活性剂相比，其特征在于我们的样品，26，27在表面活性剂，28因而不应显著测得的表面张力或CMC贡献。然而，他们是酸和能与阴离子conce干扰<html> ntration测量。在未来，其与表面活性剂浓度（ 即 ，它们是否与乙基紫，用于滴定阴离子表面活性剂染料反应）的贡献将需要被确定。如果它们的贡献是显著，额外的步骤可以被添加到所述提取方法，以消除对实例中的所有，在紫外 - 可见或通过荧光是活性的化合物中，其中将包括HULIS但不是表面活性剂。 到目前为止，对于和比本手稿提出的一个用于气雾剂的表面活性剂的表面张力曲线的气溶胶的表面张力的测定没有其它方法是可行的。建议这些测量的悬滴技术，因为它是需要具有大气样本一致的样品体积只有一个。光学技术，直接测量在微米尺寸的粒子的表面张力，没有任何萃取，正在开发中。 10，屁股="外部参照"&gt; 20,29到目前为止，它们只适用于实验室生产的颗粒，但有可能有一天被施加到大气的。 在这项工作中对表面活性剂浓度的测量呈现的比色法先前已施加到大气气溶胶样品11，13，14，30，但只有到水提取物和不增加一倍提取物，如在我们的方法。这是一个重要的区别如，如上面强调的那样，在第二萃取步骤去除如无机盐和小有机酸，其与浓度测量干扰的化合物。 6 电化学技术，最初为海水，以及较大的水性样品开发的，也被用于测量表面活性剂在ATMOS浓度pheric气溶胶。 31,32该方法是相对的， 即所得到的表面活性剂浓度取决于所选择的参考化合物和假定所有的表面活性剂的检测灵敏度是相同的。报道了该技术的检测限是0.02毫克L -1当使用四辛基苯酚乙氧基作为参考，从而0.03μM，并且与约0.05μM的用于通过比色法阴离子和阳离子表面活性剂的检测限。但是，由于在非离子和总表面活性剂浓度与比色法测定的不确定性的，这将是有趣的比较这两种方法（帧间校准）。 在提出的方法有几点可以进一步改进。 另一种染料比硫氰酸钴，将检测所有的非离子表面活性剂和机智相同的灵敏度将是非常USEFUL和减少在当前浓度测量的不确定性的主要来源。 对阳离子表面活性剂，目前估计20％的提取效率，还可以改善，因为这些化合物通常是在大气样品中的检测限。可以这样做，例如，通过使用特定的固相萃取柱。 在提取和滴定的条件可以进一步改进。例如，使用三个并联不同SPE调校，每一类的表面活性剂的最优化，可以提高提取效率，改善的方法（以下污染的风险）的质量。在SPE柱用于待分析的样品质量的最佳吸附剂密度也可被确定。用于滴定反应（pH值，添加剂）的条件也可进一步优化，以进一步提高浓度测量的灵敏度， 即 ，降低了检测限。 进一步的修改，而不是提高分析本身的质量，会带来对大气的表面活性剂，如应用的气溶胶的，而不是对所收集的所有颗粒以不同大小的级分本发明的方法（ 即亚群）的详细信息，如这里介绍。其他类型的分析也可以被施加到所述提取物，例如，LC / HR MS，串联MS或NMR来确定表面活性剂或紫外 - 可见吸收，荧光，或旋光的化学结构，以指示highly-的存在提取物中的共轭或手性化合物。

云是由地球大气层至关重要，对于大多数环境和生态系统的水文和气候系统。但它们的形成机理一些方面仍然没有完全理解，特别是存在于作为凝结核的气溶胶粒子的化学化合物的贡献。理论1预测的表面活性化合物，或表面活性剂，存在于气溶胶颗粒应强烈通过降低它们的表面张力提高云滴的形成，因此它们的形成能。但是，这些影响已经几十年仍然难以捉摸观察和表面活性剂对云的形成中的作用，目前由大气社会的很大一部分否认和忽略了所有的云调查，大气和气候模型。 对于缺乏气溶胶表面活性剂在云的形成作用的认识的一个原因是缺乏方法与异后期和表征它们。不像从其他环境样品，大气样品的分析面临挑战重复2如非常小的样品的体积和质量（这里，通常在10和100μg之间）和化学复杂性（盐，矿物质的混合物，以及众多的有机物）。为了克服这些挑战，提高气溶胶的理解表面活性剂的一些方法已经由我们的组1最近被开发的）提取具体从大气气溶胶样品的这些化合物，2）确定在气溶胶相的绝对浓度和3）确定其表面张力曲线在水，包括它们的临界胶束浓度（CMC），在该表面活性剂在表面处饱和，并且启动该浓度，以形成在本体胶束。这些方法的最新版本适用于本文件中提出。 进一步的改进和其他类型的特征中的，这可能在补偿中使用字元素到那些呈现，将被讨论。这些方法中的最近的应用已经显示出这样的分析可以如何改进在云的形成的表面活性剂的作用的认识，通过证明这一作用本身，3确定在大气气溶胶3，4，5，6和作用方式的表面活性剂浓度云滴的形成， 如图3所示 ，6证明其生物成因，3，4，第 7和由古典乐器解释他们缺乏观察。 8，9，10

<table><tbody><tr><td>Quartz filters</td><td>Fioroni</td><td></td><td>for example &amp;Oslash; 47 mm or &amp;Oslash; 150 mm, Grammage 85 g/m&lt;sup&gt;2&lt;/sup&gt;</td></tr><tr><td>Aluminium foils or glass Petri dishes</td><td></td><td></td><td>baked in oven (773 K, 6&amp;nbsp;h)</td></tr><tr><td>Tweezers, scissors</td><td></td><td></td><td></td></tr><tr><td>Desiccator</td><td></td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;SPE (Solid Phase Extraction) set-up&lt;/strong&gt;</td></tr><tr><td>SPE vacuum manifold Ac-Elut</td><td>Varian&amp;nbsp;</td><td></td><td></td></tr><tr><td>Pump Laboxat</td><td>Knf LAB</td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Nitrogen dryer set-up&lt;/strong&gt; (hand-made)</td></tr><tr><td>Compressed Nirogen 4.5 in bottle B50, 200 bar at 15 &amp;deg;C</td><td>Linde</td><td></td><td></td></tr><tr><td>Tensiometer</td><td>Dataphysics</td><td>OCA 15EC</td><td></td></tr><tr><td>Tensiometer Software</td><td></td><td>SCA software for OCA version 4-4.1</td><td></td></tr><tr><td>UV-Vis spectrometer</td><td>Agilent</td><td>8453</td><td></td></tr><tr><td>Stir-plates</td><td></td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Glassware&lt;/strong&gt;</td></tr><tr><td>Glass Petri dishes</td><td></td><td></td><td>for the water extraction step</td></tr><tr><td>Beakers</td><td></td><td></td><td></td></tr><tr><td>15 mL, 30 mL, 60 mL glass bottles with corks</td><td></td><td></td><td></td></tr><tr><td>Tubes for SPE</td><td></td><td></td><td></td></tr><tr><td>Magnetic stirring bars</td><td></td><td></td><td></td></tr><tr><td>Ultrasound bath</td><td></td><td></td><td>for glassware washing</td></tr><tr><td>Micropipettes (0.5 - 5&amp;nbsp;mL, 0.100 - 1&amp;nbsp;mL, 10 - 100 &amp;mu;L)</td><td>Rainin Pipette-Life XLS</td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Disposable small equipment&lt;/strong&gt;</td></tr><tr><td>Syringe filters 0.45 &amp;mu;m PVDF</td><td>Fisherbrand</td><td></td><td></td></tr><tr><td>SPE C18 cartridges Strata C18-E cartridges 500 mg / 3 mL&amp;nbsp;</td><td>Phenomenex</td><td></td><td></td></tr><tr><td>Plastic syringes</td><td></td><td></td><td></td></tr><tr><td>Needles</td><td></td><td></td><td></td></tr><tr><td>4 mL-vials</td><td></td><td></td><td></td></tr><tr><td>Pasteur glass pipettes</td><td></td><td></td><td></td></tr><tr><td>Micropipette tips</td><td></td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Chemicals&lt;/strong&gt;</td></tr><tr><td>Sodium dodecyl sulfate (SDS) &amp;ge; 98.5% Bioreagent</td><td>Sigma- Aldrich</td><td>L3771</td><td></td></tr><tr><td>Dioctyl sulfosuccinate sodium salt (AOT) &amp;ge; 97%</td><td>Sigma- Aldrich</td><td>323586</td><td></td></tr><tr><td>Benzyltetradecyldimethylammonium (zephiramine)&amp;nbsp; &amp;ge; 99.0% anhydrous Fluka</td><td>Sigma- Aldrich</td><td>13401</td><td></td></tr><tr><td>Cetyltrimethylammonium chloride solution (CTAC) 25 wt% in H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma- Aldrich</td><td>292737</td><td></td></tr><tr><td>(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X114) laboratory grade</td><td>Sigma- Aldrich</td><td>X114</td><td></td></tr><tr><td>Polyethylene glycol dodecyl ether (Brij35) Fluka Bio Chemika</td><td>Sigma- Aldrich</td><td>858366</td><td></td></tr><tr><td>L-&amp;alpha;-phosphatidylcholine from egg yolk type XVI-E lyophilized powder &amp;ge;&amp;nbsp;99%</td><td>Sigma- Aldrich</td><td>P3556</td><td></td></tr><tr><td>Surfactin from Bacillus subtilis &amp;ge; 98%</td><td>Sigma- Aldrich</td><td>S3523</td><td></td></tr><tr><td>R-95Dd rhamnolipid (95% dirhamnolipid, 5% monorhamnolipid)</td><td>Sigma- Aldrich</td><td>L510025</td><td></td></tr><tr><td>Ethyl violet cationic triarylmethane dye</td><td>Sigma- Aldrich</td><td>228842</td><td></td></tr><tr><td>Patent Blue VF dye content 50%</td><td>Sigma-Aldrich</td><td>198218</td><td></td></tr><tr><td>Ammonium thiocyanate &amp;ge; 99% puriss. p.a., ACS reagent</td><td>Sigma-Aldrich</td><td>31120</td><td></td></tr><tr><td>Cobalt(II) nitrate hexahydrate &amp;ge; 98% ACS reagent</td><td>Sigma-Aldrich</td><td>239267</td><td></td></tr><tr><td>Acetic anhydride &amp;ge; 99% ReagentPlus</td><td>Sigma-Aldrich</td><td>320102</td><td></td></tr><tr><td>Sodium acetate &amp;ge; 99.0% anhydrous Reagent Plus</td><td>Sigma-Aldrich</td><td>S8750</td><td></td></tr><tr><td>Ethylenediaminetetraacetic acid 99.4&amp;minus; 100.6% ACS reagent powder</td><td>Sigma-Aldrich</td><td>E9884</td><td></td></tr><tr><td>Sodium sulfate anhydrous &amp;ge; 99.0% granulated puriss. p.a. ACS reagent Fluka</td><td>Sigma-Aldrich</td><td>71960</td><td></td></tr><tr><td>Ethanol puriss. p.a. ACS Reagent reag. Ph. Eur. 96% (v/v)</td><td>Sigma-Aldrich</td><td>32294</td><td></td></tr><tr><td>Acetonitrile &amp;ge; 99.9% HiPerSolv CHROMANORM Reag. Ph. Eur. (European Pharmacopoeia Reagent) grade gradient for HPLC</td><td>VWR BDH Prolabo</td><td>20060.32</td><td>to be manipulated under hood</td></tr><tr><td>Chloroform 99% stable with 0.8&amp;minus;1% ethanol</td><td>Alfa Aesar</td><td>L13200-0F</td><td>to be manipulated under hood</td></tr><tr><td>Toluene &gt; 99%</td><td>Chimie Plus</td><td>24053</td><td>to be manipulated under hood</td></tr><tr><td>Denatured ethanol for washing</td><td></td><td></td><td></td></tr><tr><td>Ultra-Pure water</td><td>Ultrapure water system Purelab Classic, Elga</td><td></td><td></td></tr></tbody></table>

extraction and characterization of surfactants from atmospheric aerosols

预期的表面活性化合物，或表面活性剂，存在于大气气溶胶在地球大气，气象，水文中央处理液水云的形成中发挥重要作用，并为气候系统。但是，由于这些化合物的具体提取和鉴定一直缺乏了几十年，很少有人知道行动和起源的身份，性质，模式，从而防止云的形成及其与地球生态系统的潜在联系的充分理解。 在本文中，我们提出最近开发的方法1）从大气气溶胶样品的所有表面活性剂的靶向提取和对于2）它们的绝对浓度的气溶胶相中的判定和3）它们的静态的水的表面张力曲线，包括它们的临界胶束浓度（CMC）。这些方法已经被证实有9所引用的表面活性剂，我ncluding阴离子，阳离子和非离子的。结果的实施例用于在克罗地亚和建议沿海站点为今后的改进和其它表征比那些呈现讨论收集细的气溶胶颗粒（直径&lt;1μm）的发现表面活性剂。

注意:在被施加到大气样本，在本节介绍的所有协议已经9种参考表面活性剂，表面张力曲线，最小表面张力测试，并且得到的CMC是与文献极好的一致性。 21,22 1.浓度细气溶胶（&lt;1微米的直径，或"PM1"）的样品收集在石英纤维过滤器在罗戈兹尼察，克罗地亚沿海站点在2015年二月这些样品处理和提取为分别在第2和第3中，所描述的，这份手稿。为阴离子型，阳离子型和非离子型表面活性剂和气溶胶样品体积的总表面活性剂浓度，C 冲浪，P（M）的浓度，根据第4Ť测定他结果显示在图1中给出，和证据阴离子和非离子表面活性剂的测定的表面活性剂中的主导地位。 2.样品和表面张力曲线提取的表面活性剂的表面张力结合表面张力的测量，如第5和浓度测量所描述的，导致了对于相同的样品的绝对表面张力曲线， 如图2。这些曲线表明气溶胶样品中的表面活性剂浓度和这些样品的表面张力（"σMIN"），并允许以确定图形的CMC值（ 图2）。 <img alt="图1" class="xfigimg" src="/files/ftp_upload/55622/55622fig1.jpg" /> 数字1: 表面活性剂的浓度在罗戈兹尼察，克罗地亚收集细气溶胶（PM1）。阴离子（蓝色），阳离子（红色），非离子表面活性剂（绿色）和总表面活性剂浓度在气溶胶相（每个表面活性剂浓度的总和），C 冲浪，P（M）的浓度，与比色测定在细（&lt;1微米）的大气在2015年2月在罗戈兹尼察，克罗地亚沿海部位采集气溶胶方法的结果清楚地表明阴离子和非离子表面活性剂的主导地位。 <a href="http://ecsource.jove.com/files/ftp_upload/55622/55622fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" class="xfigimg" src="/files/ftp_upload/55622/55622fig2.jpg" /> 图2: 典型的表面张力曲线和CMC从气溶胶的表面活性剂罗戈兹尼察，克罗地亚。为2015年3月2日的通过组合表面张力和浓度测量所获得的样品中的表面活性剂绝对表面张力曲线。黑点代表所述表面活性剂提取物的测得的表面张力。在曲线的末端的橙色点代表气溶胶样品中的所计算出的浓度（步骤4.4.6），和"σMIN"其表面张力。 CMC的图形确定被示出。 <a href="http://ecsource.jove.com/files/ftp_upload/55622/55622fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Extraction and Characterization of Surfactants from Atmospheric Aerosols at JoVE.com

Extraction and Characterization of Surfactants from Atmospheric Aerosols

方法提出了存在于大气气溶胶的表面活性剂的靶向提取和它们的绝对浓度和表面张力曲线的测定水中，包括其临界胶束浓度（CMC）。

提取和表面活性剂的特性，从大气气溶胶

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in ...

extraction-characterization-surfactants-from-atmospheric

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JoVE Journal

Environment

16.8K 次观看.  IRCELYON, F-69626. 方法提出了存在于大气气溶胶的表面活性剂的靶向提取和它们的绝对浓度和表面张力曲线的测定水中，包括其临界胶束浓度（CMC）。 

视频: Extraction and Characterization of Surfactants from Atmospheric Aerosols

Extraction and Analysis of Microbial Phospholipid Fatty Acids in Soils

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about the overall structure of terrestrial microbial communities. PLFA profiling has been extensively used in a range of ecosystems as a biological index of overall soil quality, and as a quantitative indicator of soil response to land management and other environmental stressors.
The standard method presented here outlines four key steps: 1. lipid extraction from soil samples with a single-phase chloroform mixture, 2. fractionation using solid phase extraction columns to isolate phospholipids from other extracted lipids, 3. methanolysis of phospholipids to produce fatty acid methyl esters (FAMEs), and 4. FAME analysis by capillary gas chromatography using a flame ionization detector (GC-FID). Two standards are used, including 1,2-dinonadecanoyl-sn-glycero-3-phosphocholine (PC(19:0/19:0)) to assess the overall recovery of the extraction method, and methyl decanoate (MeC10:0) as an internal standard (ISTD) for the GC analysis.

Phospholipid fatty acids provide information about the structure of soil microbial communities. We present methods for extraction from soil samples with a single-phase chloroform mixture, fractionation of extracted lipids using solid phase extraction columns, and methanolysis to produce fatty acid methyl esters, which are analyzed by capillary gas chromatography.

提取及土壤微生物磷脂脂肪酸分析

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about ...

科研

环境科学

Production and Measurement of Organic Particulate Matter in a Flow Tube Reactor

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the production of synthetic PM for laboratory studies have become a widespread necessity. Herein, experimental protocols demonstrate approaches to produce aerosolized organic PM by &#945;-pinene ozonolysis in a flow tube reactor. Methods are described for measuring the size distributions and morphology of the aerosol particles. The video demonstrates basic operations of the flow tube reactor and related instrumentation. The first part of the video shows the procedure for preparing gas-phase reactants, ozonolysis, and production of organic PM. The second part of the video shows the procedures for determining the properties of the produced particle population. The particle number-diameter distributions show different stages of particle growth, namely condensation, coagulation, or a combination of both, depending on reaction conditions. The particle morphology is characterized by an aerosol particle mass analyzer (APM) and a scanning electron microscope (SEM). The results confirm the existence of non-spherical particles that have grown from coagulation for specific reaction conditions. The experimental results also indicate that the flow tube reactor can be used to study the physical and chemical properties of organic PM for relatively high concentrations and short time frames.

This paper describes the operation procedure for the flow tube reactor and related data collection. It shows the protocols for setting the experiments, recording data and generating the number-diameter distribution as well as the particle mass information, which gives useful information about chemical and physical properties of the organic aerosols.

流管反应器中有机颗粒物的生产与测定

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the ...

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Fizzy extraction is a new laboratory technique for analysis of volatile and semivolatile compounds. A carrier gas is dissolved in the liquid sample by applying overpressure and stirring the sample. The sample chamber is then decompressed. The analyte species are liberated to the gas phase due to effervescence.

挥发性有机化合物与大气压化学电离四极杆质谱联用

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

化学

Composition and Distribution Analysis of Bioaerosols Under Different Environmental Conditions

Variable microorganisms in particulate matter (PM) under different environmental conditions may have significant impacts on human health. In this study, we described a protocol for multiple analyses of the biological compositions in environmental PM. Five experiments are presented: (1) PM number monitoring by using a laser particle counter; (2) PM collection by using a cyclonic aerosol sampler; (3) PM collection by using a high-volume air sampler with filters; (4) culturable microbes collection by the Andersen six-stage sampler; and (5) detection of biological composition of environmental PM by bacterial 16SrDNA and fungal ITS region sequencing. We selected hazy days and a livestock farm as two typical examples of the application in this protocol. In this study, these two sampling methods, cyclonic aerosol sampler and filter sampler, showed different sampling efficiency. The cyclonic aerosol sampler performed much better in terms of collecting bacteria, while these two methods showed the same efficiency in collecting fungi. Filter samplers can work under low temperature conditions while cyclonic aerosol samplers have a sampling limitation for temperature. A solid impacting sampler, such as an Andersen six-stage sampler, can be used to sample bioaerosols directly into the culture medium, which increases the survival rate of culturable microorganisms. However, this method mainly relies on culture while more than 99% of microbes cannot be cultured. DNA extracted from the culturable bacteria collected by the Andersen six-stage sampler and samples collected by cyclonic aerosol sampler and filter sampler were detected by bacterial 16S rDNA and fungal ITS region sequencing.All the methods above may have wide application in many fields of study, such as environmental monitoring and airborne pathogen detection. From these results, we can conclude that these methods can be used under different conditions and may help other researchers further explore the health impacts of environmental bioaerosols.

Understanding the biological composition of environmental particulate matter is important for the study of its significant impacts on human health and disease spread. Here, we used three types of bioaerosol sampling methods and a biological analysis of airborne microbes to better explore airborne microbial communities under different environmental conditions.

不同环境条件下生物气溶胶的组成及分布分析

Variable microorganisms in particulate matter (PM) under different environmental conditions may have significant impacts on human health. In this study, ...

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

由烃类和氟碳油组成的同液滴的自由基聚合制备空心聚苯乙烯颗粒和微胶囊

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

Enhanced Oil Recovery using a Combination of Biosurfactants

Biosurfactants are surface-active compounds capable of reducing the surface tension between two phases of different polarities. Biosurfactants have been emerging as promising alternatives to chemical surfactants due to less toxicity, high biodegradability, environmental compatibility and tolerance to extreme environmental conditions. Here, we illustrate the methods used for screening of microbes capable of producing biosurfactants. The biosurfactant producing microbes were identified using drop collapse, oil spreading, and emulsion index assays. Biosurfactant production was validated by determining the reduction in surface tension of the media due to growth of the microbial members. We also describe the methods involved in characterization and identification of biosurfactants. Thin layer chromatography of the extracted biosurfactant followed by differential staining of the plates was performed to determine the nature of the biosurfactant. LCMS, 1H NMR, and FT-IR were used to chemically identify the biosurfactant. We further illustrate the methods to evaluate the application of the combination of produced biosurfactants for enhancing residual oil recovery in a simulated sand pack column.

We illustrate the methods involved in screening and identification of the biosurfactant producing microbes. Methods for chromatographic characterization and chemical identification of the biosurfactants, determining the industrial applicability of the biosurfactant&#160;in enhancing residual oil recovery are also presented.

使用生物表面活性剂组合提高石油采收率

Biosurfactants are surface-active compounds capable of reducing the surface tension between two phases of different polarities. Biosurfactants have been ...

Studying Surfactant Effects on Hydrate Crystallization at Oil-Water Interfaces Using a Low-Cost Integrated Modular Peltier Device

We introduce an approach to study the formation and growth of hydrates under the influence of nonionic surfactants. The experimental system includes a temperature regulator, visualization techniques, and inner pressure measurements. The temperature control system contains a low-cost, programmable temperature regulator made with solid-state Peltier components. Along with the temperature control system, we incorporated visualization techniques and internal pressure measurements to study hydrate formation and inhibition in the presence of nonionic surfactants. We studied the hydrate-inhibiting ability of nonionic surfactants (sorbitane monolaurate, sorbitane monooleate, PEG-PPG-PEG, and polyoxyethylenesorbitan tristearate) at low (i.e., 0.1 CMC), medium (i.e., CMC), and high (i.e., 10 CMC) concentrations. Two types of crystals were formed: planar and conical. Planar crystals were formed in plain water and low surfactant concentrations. Conical crystals were formed in high surfactant concentrations. The results of the study show that conical crystals are the most effective in terms of hydrate inhibition. Because conical crystals cannot grow past a certain size, the hydrate growth rate as a conical crystal is slower than the hydrate growth rate as planar crystal. Hence, surfactants that force hydrates to form conical crystals are the most efficient. The goal of the protocol is to provide a detailed description of an experimental system that is capable of investigating the cyclopentane hydrate crystallization process on the surface of a water droplet in the presence of surfactant molecules.

We present a protocol to study the formation of hydrates in the presence of nonionic surfactants on the interface of a water droplet submerged in cyclopentane. The protocol consists of building a low-cost, programmable, temperature regulator. The temperature control system is combined with visualization techniques and internal pressure measurements.

使用低成本集成模块化 Peltier 器件研究油水界面水合物结晶的超活性剂效应

We introduce an approach to study the formation and growth of hydrates under the influence of nonionic surfactants. The experimental system includes a ...

Capturing Actively Produced Microbial Volatile Organic Compounds from Human-Associated Samples with Vacuum-Assisted Sorbent Extraction

Volatile organic compounds (VOCs) from biological samples have unknown origins. VOCs may originate from the host or different organisms from within the host&#39;s microbial community. To disentangle the origin of microbial VOCs, volatile headspace analysis of bacterial mono- and co-cultures of Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii, and stable isotope probing in biological samples of feces, saliva, sewage, and sputum were performed. Mono- and co-cultures were used to identify volatile production from individual bacterial species or in combination with stable isotope probing to identify the active metabolism of microbes from the biological samples.
Vacuum-assisted sorbent extraction (VASE) was employed to extract the VOCs. VASE is an easy-to-use, commercialized, solvent-free headspace extraction method for semi-volatile and volatile compounds. The lack of solvents and the near-vacuum conditions used during extraction make developing a method relatively easy and fast when compared to other extraction options such as tert-butylation and solid phase microextraction. The workflow described here was used to identify specific volatile signatures from mono- and co-cultures. Furthermore, analysis of the stable isotope probing of human associated biological samples identified VOCs that were either commonly or uniquely produced. This paper presents the general workflow and experimental considerations of VASE in conjunction with stable isotope probing of live microbial cultures.

This protocol describes the extraction of volatile organic compounds from a biological sample with the vacuum-assisted sorbent extraction method, gas chromatography coupled with mass spectrometry using the Entech Sample Preparation Rail, and data analysis. It also describes culture of biological samples and stable isotope probing.

通过真空辅助吸附剂提取从人类相关样品中捕获活性产生的微生物挥发性有机化合物

Volatile organic compounds (VOCs) from biological samples have unknown origins. VOCs may originate from the host or different organisms from within the ...

生物化学

Solid-Liquid Extraction

Source: Laboratory of Dr. Jay Deiner &#8212; City University of New York
Extraction is a crucial step in most chemical analyses. It entails removing the analyte from its sample matrix and passing it into the phase required for spectroscopic or chromatographic identification and quantification. When the sample is a solid and the required phase for analysis is a liquid, the process is called solid-liquid extraction. A simple and broadly applicable form of solid-liquid extraction entails combining the solid with a solvent in which the analyte is soluble. Through agitation, the analyte partitions into the liquid phase, which may then be separated from the solid through filtration. The choice of solvent must be made based on the solubility of the target analyte, and on the balance of cost, safety, and environmental concerns.

Solid-Liquid Extraction: Principle, Procedure, Applications

固-液萃取

Source: Laboratory of Dr. Jay Deiner &#8212; City University of New York
Extraction is a crucial step in most chemical analyses. It entails removing the ...

教育

JoVE Science Education

有机化学

Soxhlet Extraction of Lipid Biomarkers from Sediment

Source: Laboratory of Jeff Salacup&#160;- University of Massachusetts Amherst
Every lab needs standards that track the performance, accuracy, and precision of its instruments over time to ensure a measurement made today is the same as a measurement made a year from now (Figure 1). Because standards must test the performance of instruments over a long period of time, large volumes of the standards are often required. Many chemical standards can be purchased from retail scientific companies, like Sigma-Aldrich and Fisher. However, some compounds that occur in nature and that are relevant to paleoclimatic studies have not yet been isolated and purified for purchase. Therefore, these compounds need to be extracted from natural samples, and because of the large volumes of standards required, large volumes of sediment need to be extracted. The Accelerated Solvent Extraction (Dionex) and sonication extractions are not appropriate for the extraction of such large sediment volumes. In these circumstances, a Soxhlet extraction is used.
<img alt="Figure 1" src="/files/ftp_upload/10096/10096fig1.jpg" /> 
Figure 1. Schematic depicting how chemical standard tracks the performance of an instrument through time. The dashed line represents a 1:1 relationship between the accepted and measured (on the instrument) value of a variable. Each star is a weekly measurement of the chemical standard. Green stars represent standards that are accurate. Red stars reflect those that are not accurate indicating that the instrument requires corrective maintenance.