Advanced Techniques for Organic Analysis

研究的重点将是高效多维分离的进展，包括全二维气相色谱(GC×GC)和液相色谱(LC×LC)。这项研究的目标包括通过非常规方法提高分离的速度和效率。将进一步发展空气中挥发性有机化合物的被动采样，特别注重土壤气体分析。 我们开发了一种用于GC×GC的新型热调制器，它不需要制冷剂或移动部件。它的基础是一段停用的不锈钢管子，上面涂有一层专利涂层，由通过热处理聚二甲基硅氧烷(PDMS)获得的二氧化硅纳米颗粒组成。我们将尝试通过加入具有大比表面积和高吸附能力的碳基纳米材料来显著提高涂层的容量。这些材料将包括纳米钻石，它在机械和热稳定性方面极其稳定，在所有材料中具有最高的导热系数，以及石墨烯/氧化石墨烯，它以极高的吸附能力和高热稳定性而闻名。我们还计划探索溶胶-凝胶化学来结合纳米材料，并增加调制器内的活性相的数量。 现代的小颗粒高效液相色谱柱提供了非常有效的分离，但需要非常高的压力来驱动流动相。我们将探索滑铁卢大学Eric Prouzet博士开发的一种新型固定相颗粒，这种颗粒结合了亚微米尺寸和非常高的中间孔隙率，使它们非常具有渗透性。我们希望用这些颗粒填充的色谱柱能在相对适度的背压下提供非凡的效率。将探索这些色谱柱在环境分析中的应用。 LC×LC仍然是一种开发中的技术，特别是在其在线版本中。我们将利用我们在GC×GC领域获得的经验来推动这项技术的发展。特别是，我们将专注于通过使用填充了上述纳米颗粒的非常短(但高效)的柱来提高二维分离的速度。将使用非常快的梯度，在极低体积的专有微型制造混合器的帮助下产生。我们还将探索热调制在LC×LC中的应用。其他小组报告的关于该方法适用性的初步结果看起来非常有希望，我们在热调制领域的专业知识应该是毋庸置疑的资产。 人们越来越需要廉价的工具来表征污染场地的土壤气体。本课题组开发的基于PDMS的渗透被动采样器已被用于这一目的，并取得了一定的成功，但由于饥饿效应，其在低渗透介质中的性能受到影响。我们计划开发一种新的基于平衡采样的土壤气体分析方法。一根涂有一层相对较厚的PDMS的玻璃棒将使用专门设计的探头暴露在土壤气体中。在足够长的时间后，PDMS涂层将与周围大气达到平衡，涂层中分析物的浓度将与其在土壤气体中的浓度成正比。探测器将允许采样器与大气隔离以进行回收。然后，采样器将被转移到装有吸着剂的热解吸管中，以便运输到实验室。任何可能在运输过程中从PDMS中解吸出来的分析物都会被吸着剂捕获，因此样品的完整性将得到保护。如果成功，这种方法具有巨大的商业化潜力。

The main thrust of the research will be the advancement of high efficiency and multidimensional separations, including comprehensive two-dimensional gas chromatography (GC×GC) and liquid chromatography (LC×LC). The goals of the research include increasing the speed and efficiency of the separations through unconventional approaches. Passive sampling of volatile organic compounds in air will be further developed with a particular focus on soil gas analysis. We have developed a novel thermal modulator for GC×GC requiring no cryogens or moving parts. It is based on a segment of deactivated stainless steel tubing coated with a proprietary coating consisting of silica nanoparticles obtained through thermal treatment of polydimethylsiloxane (PDMS). We will attempt to significantly increase the capacity of the coating through incorporation of carbon-based nanomaterials characterized by large surface areas and high sorption capacities. These will include nanodiamonds, which are extremely mechanically and thermally stable and have the highest heat conductivity of all materials, as well as graphene/graphene oxide, known for very high sorption capacity and high thermal stability. We also plan to explore sol-gel chemistry to incorporate the nanomaterials and increase the amount of the active phase inside the modulator. Modern small particle columns in HPLC provide very efficient separations, but require very high pressures to drive the mobile phase. We will explore a new class of stationary phase particles developed by Dr. Eric Prouzet from the University of Waterloo, which combine sub-micron size with very high intermediate porosity, making them very permeable. We expect columns packed with these particles to offer exceptional efficiency at relatively modest backpressures. Applications of these columns in environmental analysis will be explored. LC×LC remains a technique under development, especially in its on-line version. We will use our experience gained in the area of GC×GC to advance the technique. In particular, we will focus on increasing the speed of second-dimension separations through the use of very short (but highly efficient) columns packed with the nanoparticles described above. Very fast gradients will be used, generated with the help of proprietary microfabricated mixers of extremely low volume. We will also explore the use of thermal modulation in LC×LC. Preliminary results on the suitability of the approach reported by other groups look very promising, and our expertise in the area of thermal modulation should be an unquestionable asset. There is a growing need for inexpensive tools for the characterization of soil gas at polluted sites. PDMS-based permeation passive samplers developed by our group have been adopted for this purpose with some success, but their performance suffers in low permeability media because of the starvation effect. We plan to develop a novel approach to soil gas analysis based on equilibrium sampling. A glass rod coated with a relatively thick layer of PDMS will be exposed to the soil gas using a specially designed probe. After a sufficiently long time the PDMS coating will reach equilibrium with the surrounding atmosphere, and the concentration of the analytes in the coating will be proportional to their concentration in the soil gas. The probe will allow isolating the sampler from the atmosphere for retrieval. The sampler will then be transferred to a thermal desorption tube containing a sorbent for transport to the laboratory. Any analyte that could potentially desorb from the PDMS during transport will be trapped by the sorbent, hence integrity of the sample will be preserved. If successful, this method has a tremendous potential for commercialization.