Thompson Christopher J, Riley Robert G, Amonette James E, Gassman Paul L
Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
Appl Spectrosc. 2006 Aug;60(8):914-9. doi: 10.1366/000370206778062156.
On-line Fourier transform infrared (FT-IR) spectroscopy was applied to monitor the concentration of halogenated volatile organic compounds in a sample-preparation process that simulates long-term, slow accumulation of contaminants in soils (i.e., aging). Artificial aging is conducted by circulating a supercritical fluid solution containing the contaminant(s) of interest through a packed soil column. Mid-infrared spectra of several volatile halocarbons were measured in supercritical Xe and CO(2) to evaluate possible interferences from the strong absorption of CO(2). Although some of the C-X bands were partially masked in supercritical CO(2), all of the compounds studied had distinct spectral features in the region 1400-700 cm(-1) and could be monitored in either solvent. Quantitative measurements of halogenated volatile organics in supercritical CO(2) were demonstrated with CCl(4). Excellent results were obtained over the range 7-280 mM. Representative artificial aging experiments were conducted on two test soils using CCl(4) as the contaminant. On-line (FT-IR) estimates of the aged soil concentrations were 1.3-4.4 times higher than off-line concentrations obtained by gas chromatography/mass spectrometry. The discrepancies were primarily ascribed to post-aging losses that occurred during depressurization and subsequent sample handling. FT-IR spectroscopy is shown to be a powerful tool for monitoring soil loading behavior and for developing artificial aging protocols.
在线傅里叶变换红外（FT-IR）光谱法被用于监测样品制备过程中卤代挥发性有机化合物的浓度，该过程模拟了土壤中污染物的长期缓慢积累（即老化）。人工老化是通过使含有目标污染物的超临界流体溶液在填充土壤柱中循环来进行的。在超临界Xe和CO₂中测量了几种挥发性卤代烃的中红外光谱，以评估来自CO₂强吸收的可能干扰。尽管在超临界CO₂中一些C-X带被部分掩盖，但所研究的所有化合物在1400 - 700 cm⁻¹区域都有明显的光谱特征，并且可以在任何一种溶剂中进行监测。用CCl₄对超临界CO₂中的卤代挥发性有机物进行了定量测量。在7 - 280 mM范围内获得了优异的结果。使用CCl₄作为污染物对两种测试土壤进行了代表性的人工老化实验。老化土壤浓度的在线（FT-IR）估计值比气相色谱/质谱法获得的离线浓度高1.3 - 4.4倍。差异主要归因于减压和后续样品处理过程中发生的老化后损失。FT-IR光谱法被证明是监测土壤负载行为和制定人工老化方案的有力工具。
