Abstract

The measurement of aerosol acidity is important to have a comprehensive understanding of aerosol chemistry, the adverse health effects of particulate matter, and climate. The Colorimetry Integrated with CAMera (CICAM) method is demonstrated to detect the color change of a filter (impregnated with an acid indicator), after the application of an acidic aerosol, using digital images. The CICAM images were analyzed by a computer program that employs the Matplotlib Library in python to decouple the camera image to the Red-Green-Blue (RGB) scale. The calibration of the CICAM method for the detection of proton concentration ([H⁺], mol L⁻¹) in aerosol was performed with regard to the change of the G color component. The Colorimetry integrated with Reflective UV spectrometry (C-RUV) method that has recently been developed to detect [H⁺] in aerosol collected on a dyed filter using a micro-UV spectrometer can provide a lower uncertainty and a limit of detection that is an order of magnitude lower than the CICAM method, but is significantly more expensive. The CICAM method allows for the online detection of aerosol acidity utilizing a commercialized camera and LED light. The relationship between CICAM and C-RUV was also demonstrated by translating C-RUV spectral data into RGB values. Remarkably, the Green values measured by CICAM were statistically similar to the Green values obtained from C-RUV data. Therefore, we conclude that the CICAM and C-RUV method are comparable in their use for the prediction of proton concentration.

Copyright © 2021 American Association for Aerosol Research

摘要

气溶胶酸度的测量对于全面了解气溶胶化学、颗粒物对健康的不利影响和气候非常重要。与 CAMera 集成的比色法 (CICAM) 方法被证明可以使用数字图像检测过滤器（浸渍有酸性指示剂）在施加酸性气溶胶后的颜色变化。CICAM 图像由计算机程序分析，该程序使用 Python 中的 Matplotlib 库将相机图像解耦为红-绿-蓝 (RGB) 比例。用于检测质子浓度 ([H ⁺ ], mol L ^-1) 在气溶胶中进行了关于 G 颜色分量的变化。比色法与反射紫外光谱法 (C-RUV) 相结合，该方法最近被开发用于检测 [H ⁺] 在使用微型紫外光谱仪在染色过滤器上收集的气溶胶中，可以提供较低的不确定性和检测限，这比 CICAM 方法低一个数量级，但要贵得多。CICAM 方法允许使用商业化的相机和 LED 灯在线检测气溶胶酸度。CICAM 和 C-RUV 之间的关系还通过将 C-RUV 光谱数据转换为 RGB 值来证明。值得注意的是，CICAM 测量的绿色值与从 C-RUV 数据获得的绿色值在统计上相似。因此，我们得出结论，CICAM 和 C-RUV 方法在用于预测质子浓度方面具有可比性。

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