Technical Note: Determination of formaldehyde mixing ratios in air with PTR-MS: laboratory experiments and field measurements S. Inomata1, H. Tanimoto1, S. Kameyama1,2, U. Tsunogai3, H. Irie4, Y. Kanaya4, and Z. Wang5 1National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan 2JSPS Research Fellow, Japan 3Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan 4Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Yokohama, Kanagawa 236-0001, Japan 5LAPC/NZC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 10029, China
Abstract. Formaldehyde (HCHO), the most abundant carbonyl compound in the atmosphere,
is generated as an intermediate product in the oxidation of nonmethane
hydrocarbons. Proton transfer reaction mass spectrometry (PTR-MS) has the
capability to detect HCHO from ion signals at m/z 31 with high time-resolution.
However, the detection sensitivity is low compared to other detectable
species, and is considerably affected by humidity, due to back reactions
between protonated HCHO and water vapor prior to analysis. We performed a
laboratory calibration of PTR-MS for HCHO and examined the detection
sensitivity and humidity dependence at various field strengths.
Subsequently, we deployed the PTR-MS instrument in a field campaign at Mount
Tai in China in June 2006 to measure HCHO in various meteorological and
photochemical conditions; we also conducted intercomparison measurements by
Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS).
Correction of interference in the m/z 31 signals by fragments from proton
transfer reactions with methyl hydroperoxide, methanol, and ethanol greatly
improves agreement between the two methods, giving the correlation
[HCHO]MAX-DOAS=(0.99±0.16) [HCHO]PTR-MS+(0.02±0.38), where error limits represent 95% confidence levels.
Citation: Inomata, S., Tanimoto, H., Kameyama, S., Tsunogai, U., Irie, H., Kanaya, Y., and Wang, Z.: Technical Note: Determination of formaldehyde mixing ratios in air with PTR-MS: laboratory experiments and field measurements, Atmos. Chem. Phys., 8, 273-284, doi:10.5194/acp-8-273-2008, 2008.