Effect of Secondary HCHO and Ozone Formation during SIJAQ 2021 Campaign - Analysis of HCHO-2,4-DNPH Using LC/QTOF

Scientific analyses were carried out to determine the effect of ozone formation based on volatile organic compounds (VOCs) at the central area of Seoul from October 17 to November 11 in 2021 during Satellite Integrated Joint monitoring of Air Quality (SIJAQ 2021) campaign. VOCs including formaldehyde (HCHO) can be emitted by biogenic, primary emission, and secondary formation in urban areas. In this study, HCHO were collected using a 4-hr integrated sequence sampler equipped absorption tubes including 2,4-dinitrophenylhydrazine (DNPH). Liquid Chromatography/Quadruple Time Of Flight (LC/QTOF) was utilized to determine the quantitative analysis of HCHO. As a result, overall average of HCHO is presented as 7.4 ppb, which is about 2.4 times higher than toluene concentrations. Strong diurnal pattern as in day-time maximum indicates that secondary HCHO is dominant. A quarter of measured ozone could be originated from HCHO from ozone formation potential model. The current result can be applied to reduction strategies for ozone and verification of satellite HCHO monitoring.