Imaging spectroscopy combines the spatial discrimination of imaging techniques with the chemical information of spectroscopy to form a powerful tool for the study of chemically heterogeneous systems. This work describes the in situ qualitative and quantitative analysis of contaminant transport flow cells and of high-performance thin-layer chromatography (HPTLC) plates by near-infrared imaging spectroscopy.; A solid-state, near-infrared imaging spectrometer was constructed for these studies. The spectrometer utilized an imaging quality acousto-optic tunable filter for wavelength selection over the 1.3–2.3 μ range and a cryogenically cooled, 240 x 324 pixel platinum silicide camera for detection. Samples were analyzed by either diffuse reflectance or diffuse transmittance using a 250 W quartz-tungsten-halogen lamp for sample illumination.; The first series of investigations focused on the analysis of laboratory-scale flow cells, which are used to study the transport of non-aqueous phase liquid (NAPL) contaminants in the soil and groundwater. Current detection systems used for determining NAPL distribution are incapable of distinguishing between chemical components in NAPL mixtures, limiting flow cell experiments to the study of simple systems. This research utilized the near-infrared imaging spectrometer and multivariate calibration techniques to quantitatively determine the concentrations of individual constituents in binary NAPL mixtures within vadose zone and aquifer models. The vadose zone calibration data was used to determine the spatial distribution of each NAPL constituent in situ during a dynamic, multi-component flow cell experiment that modeled the remediation of NAPL contaminated soil. This technique, the first to quantitatively determine the in situ distribution of the individual NAPL phase constituents, represents the state of the art in detection for contaminant transport flow cells.; The second series of investigations focused on analysis of samples on HPTLC plates. Conventional systems require visualization techniques to detect compounds lacking a chromophore or fluorophore. This research utilized the near-infrared imaging spectrometer as a non-destructive detection technique to provide qualitative and quantitative information for caffeine samples on HPTLC plates. Both diffuse reflectance and diffuse transmittance measurements provided detection limits of several micrograms. The caffeine spectrum was clearly distinguishable down to 25 μg using a diffuse reflectance geometry with a mirrored backing applied to the HPTLC plate.
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机译：成像光谱学将成像技术的空间辨别力与光谱学的化学信息结合在一起，形成了研究化学异质系统的有力工具。这项工作描述了通过近红外成像光谱法对污染物传输流动池和高性能薄层色谱（HPTLC）板的原位定性和定量分析。为这些研究构建了固态，近红外成像光谱仪。该光谱仪利用成像质量的声光可调滤光片在1.3–2.3μ范围内进行波长选择，并使用低温冷却的240 x 324像素硅化铂硅摄像机进行检测。使用250 W的石英-钨-卤素灯通过漫反射率或漫透射率分析样品，以进行样品照明。第一系列研究集中于分析实验室规模的流通池，这些流通池用于研究土壤和地下水中非水相液体（NAPL）污染物的迁移。当前用于确定NAPL分布的检测系统无法区分NAPL混合物中的化学成分，从而将流通池实验仅限于简单系统的研究。这项研究利用近红外成像光谱仪和多元校准技术定量确定了渗流带和含水层模型中二元NAPL混合物中各个成分的浓度。渗流区校准数据用于在动态，多组分流动池实验中确定NAPL污染土壤的修复过程，从而确定每个NAPL成分的原位“ italic”的空间分布。该技术是第一种定量确定各个NAPL相成分的就地分布的技术，它代表了检测污染物传输流动池的最新技术。第二系列的研究重点是分析HPTLC板上的样品。常规系统需要可视化技术来检测缺少发色团或荧光团的化合物。这项研究利用近红外成像光谱仪作为非破坏性检测技术，以提供HPTLC板上咖啡因样品的定性和定量信息。漫反射率和漫透射率测量均提供了几微克的检测极限。使用漫反射几何结构并在HPTLC板上施加镜面背衬，咖啡因光谱可清晰地区分至25μg。
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