EC-19. New directions in the measurements of organic nitrates: field observations and lab studies
Organic nitrates are an important component of the nitrogen oxide (NOx = NO + NO2) cycle. The yields and fates of organic nitrates (ONs) play a critical role in air quality, human health and climate through their coupling to regional NOx, ozone and secondary organic aerosol. There has been extensive work to measure ONs in the atmosphere and in laboratory studies. Much of this work lacks accurate calibration due to the complexity, sheer quantity of molecular formula observed and the lack of accessible standards. In order to calibrate the NOAA Iodide (I-) chemical ionization mass spectrometer (CIMS) for specific ONs, synthesis and quantification of these molecules was conducted. The Pasadena, CA ground site work during the SUNVEx experiment, helps reduce the scope of this task to a manageable list of relevant compounds for an urban atmosphere. A select suite of molecules, namely isoprene hydroxy nitrates (C5H9NO5) and methyl vinyl ketone nitrates (C4H7NO5), were synthesized via epoxide ring opening chemistry in the presence of HNO3. Quantification of these ONs sources was conducted using a GC-NOy system. Here we report the synthesis, calibration and ambient observations of these ONs.