Advanced Techniques for Organic Analysis

该研究的主要方向将是高效多维分离技术的发展，包括全面的二维气相色谱（GC×GC）和液相色谱（LC×LC）。研究的目标包括通过非常规方法提高分离的速度和效率。将进一步发展对空气中挥发性有机化合物的被动采样，特别侧重于土壤气体分析。 我们研制了一种用于GC×GC的新型热调制器，它不需要制冷剂和运动部件。它基于一段钝化不锈钢管，涂有专有涂层，由通过聚二甲基硅氧烷（PDMS）热处理获得的二氧化硅纳米颗粒组成。我们将尝试通过结合具有大表面积和高吸附能力的碳基纳米材料来显着增加涂层的容量。这些将包括纳米金刚石，其具有极高的机械和热稳定性，并且具有所有材料中最高的导热性，以及石墨烯/氧化石墨烯，以非常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，将纳米材料和增加调制器内的活性相的量。 HPLC中的现代小颗粒柱提供非常有效的分离，但需要非常高的压力来驱动移动的相。我们将探索由滑铁卢大学的Eric Prouzet博士开发的一类新型固定相颗粒，该颗粒将联合收割机亚微米尺寸与非常高的中间孔隙率相结合，使其具有非常高的渗透性。我们期望填充有这些颗粒的柱在相对适度的背压下提供卓越的效率。将探讨这些色谱柱在环境分析中的应用。 LC×LC仍然是一种正在开发的技术，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进这项技术。特别是，我们将专注于通过使用填充有上述纳米颗粒的非常短（但高效）的柱来提高第二维分离的速度。将使用非常快的梯度，在极低体积的专有微制造混合器的帮助下产生。我们还将探讨热调制在LC×LC中的应用。其他小组报告的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一个不容置疑的资产。 越来越需要廉价的工具来表征污染场地的土壤气体。我们小组开发的基于PDMS的渗透被动采样器已被用于此目的，取得了一定的成功，但由于饥饿效应，它们的性能在低渗透介质中受到影响。我们计划开发一种基于平衡采样的土壤气体分析新方法。使用专门设计的探针将涂有相对厚的PDMS层的玻璃棒暴露于土壤气体。在足够长的时间之后，PDMS涂层将与周围大气达到平衡，并且涂层中分析物的浓度将与其在土壤气体中的浓度成比例。探测器将允许将采样器与大气隔离，以便取回。然后将采样器转移到含有吸附剂的热解吸管中，以便运输到实验室。在运输过程中可能从PDMS解吸的任何分析物将被吸附剂捕获，因此将保持样品的完整性。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.