We use a custom-built chemical ionization mass spectrometer with triple-quadrupole mass analyzer that is modeled after the CIMS developed by the Wennberg group at Caltech. The CIMS operates using the CF3O- reagent ion and can detect a large range of volatile organic compounds from the following classes: (1) H2O2 and organic hydroperoxides, (2) acidic compounds such as SO2, HCN, HNO3, and organic acids, (3) polyols (glycol, methyltetrols), (4) hydroxy epoxides (e.g., IEPOX), (5) hydroxy carbonyls (e.g., glycolaldehyde, hydroxyacetone), (6) hydroxy nitrates (e.g., isoprene and pinene nitrates), and (7) other multifunctional compounds (e.g., nitrooxy hydroperoxides). We are in the process of building a CIMS using an Ionicon time-of-flight mass analyzer.