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Low Cost Detection Method for in Situ Detection of Aerosol Acidity Using Colorimetry Integrated With Camera
AZAD MADHU, Myoseon Jang, Zechen Yu, University of Florida
Abstract Number: 246
Working Group: Instrumentation and Methods
Abstract
Despite numerous studies that report the association of aerosol acidity with health effects of particulates and aerosol chemistry, the online detection of aerosol acidity is expensive and inaccessible. The Colorimetry integrated with Reflective UV Spectrometer (C-RUV) method has recently been developed to detect the aerosol acidity collected on a filter. This method innovates the online detection of aerosol acidity by using a micro-UV spectrometer that can be easily deployable in the field. However, the micro-UV spectrometer is still costly. In this study, a low-cost detection method that utilizes a commercialized camera (i.g., cellphone camera) with an LED light is demonstrated to measure aerosol acidity. The Colorimetry integrated with Camera (CICAM) images are used for the detection of the color change by the acidic aerosol collected in a filter that is impregnated with acid indicator (metanil yellow). Then, the resulting CICAM images are decoupled to the typical RGB (Red-Green-Blue) scale using a python-based computer program. The color change in the indicator of this study is most dramatic in the G component. Therefore, the calibration of the acidity of aerosol samples is performed with regard to the G value. In order to develop the relationship between CICAM and C-RUV, the spectral data originating from a micro-UV spectrometer is translated into the RGB values under the LED light source that is used for CICAM. There is a strong linearity between CICAM calibration and C-RUV. Therefore the previously derived C-RUV calibration can be directly applied to CICAM with a simple coefficient. The CICAM method and device are also applied to field data. Because of a user-friendly, easily deployable technique, the CICAM method will allow for field monitoring of aerosol acidity as well as citizen science.