| Proton transfer reaction mass spectrometry (PTR-MS) has been shown to be a reliable and efficient method for determining atmospheric mixing ratios of volatile organic compounds (VOCs). As a part of AIRMAP, two PTR-MS instruments were used in field and laboratory studies. A high sensitivity instrument showed improved limits of detection by 3-5 times when compared to a standard sensitivity instrument. Agreement for quantification of VOCs by PTR-MS to other methods was good. Average atmospheric mixing ratios, diurnal profiles, and deposition velocities of methanol, acetone, acetaldehyde, acetic acid, isoprene, alpha-pinene, beta-pinene, methylethyl ketone, methylvinyl ketone and methacrolein were determined at two locations in New England. Laboratory studies utilizing an environmental chamber and PTR-MS were used to identify and quantify products from the chlorine initiated oxidation of alpha- and beta-pinene. Products observed in the oxidation of alpha-pinene included pinonaldehyde (8%) and acetone (10%), and acetone (10%) for the beta-pinene case. |
