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Aerosol analysis using quantum cascade laser infrared spectroscopy: Application to crystalline silica measurement
Journal of Aerosol Science ( IF 4.5 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.jaerosci.2020.105643
Shijun Wei , Pramod Kulkarni , Lina Zheng , Kevin Ashley

Abstract A method for trace analysis of aerosol mineral components using quantum cascade laser (QCL) based infrared absorption spectroscopy is described. The measurement approach involves: (a) collection of aerosol on a particulate filter; (b) sample treatment using low-temperature oxygenated plasma to minimize the matrix interferences; (c) redeposition of the treated sample as a dried spot for direct-on-filter analysis; and (d) infrared transmittance measurement of the dried spot using the QCL and mercury-cadmium-telluride detector. The method was applied to quantification of trace α-quartz in workplace aerosols. Infrared absorbance spectra in the range 750–1030 cm−1 were obtained using the QCL instrument; the characteristic peak of α-quartz at 798 cm−1 was used to measure its content. A correction scheme was applied to account for spectral interference from kaolinite mineral for coal dust samples. The detection limit for α-quartz was estimated to be 0.12 μg for a dried spot diameter of 1 mm. This detection limit is an order-of-magnitude lower than those attainable by the current standard X-ray diffraction (XRD) or Fourier transform infrared spectroscopy (FTIR) methods involving similar sample preparation and treatment. The QCL method was extended to the measurement of respirable α-quartz concentrations in workplace aerosols released during cutting of fiber-reinforced cement and engineered stone products (used in building construction), as well as those from various coal mine dusts. The measurements compared well with those from the standard XRD method, even for samples with matrix and mineral interferences. The results show that QCL-based IR transmission spectroscopy can offer sensitive, trace-level measurement of aerosol mineral components.

中文翻译:

使用量子级联激光红外光谱进行气溶胶分析:在结晶二氧化硅测量中的应用

摘要 描述了一种使用基于量子级联激光 (QCL) 的红外吸收光谱法对气溶胶矿物成分进行痕量分析的方法。测量方法包括: (a) 在微粒过滤器上收集气溶胶;(b) 使用低温氧化等离子体处理样品以尽量减少基质干扰;(c) 将处理过的样品重新沉积为干燥点,用于直接过滤分析;(d) 使用 QCL 和汞-镉-碲检测器对干燥点的红外透射率测量。该方法用于量化工作场所气溶胶中的痕量 α-石英。使用 QCL 仪器获得 750-1030 cm-1 范围内的红外吸收光谱;α-石英在 798 cm-1 处的特征峰用于测量其含量。应用校正方案来解释高岭石矿物对煤尘样品的光谱干扰。对于 1 mm 的干斑直径,α-石英的检测限估计为 0.12 μg。该检测限比当前标准 X 射线衍射 (XRD) 或涉及类似样品制备和处理的傅立叶变换红外光谱 (FTIR) 方法可达到的检测限低一个数量级。QCL 方法扩展到测量纤维增强水泥和人造石制品(用于建筑施工)以及各种煤矿粉尘的切割过程中释放的工作场所气溶胶中的可吸入 α-石英浓度。测量结果与标准 XRD 方法的测量结果相得益彰,即使对于具有基质和矿物干扰的样品也是如此。
更新日期:2020-12-01
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