ION MOBILITY SPECTROMETRY OF HYDRAZINE, MONOMETHYLHYDRAZINE, AND AMMONIA IN AIR WITH 5-NONANONE REAGENT GAS

Hydrazine (HZ) and monomethylhydrazine (MMH) in air were monitored con tinuously using a hand-held ion mobility spectrometer equipped with me mbrane inlet, Ni-63 ion source, acetone reagent gas, and ambient tempe rature drift tube. Response characteristics included detection limit, 6 ppb; linear range, 10-600 ppb; saturated response, >2 ppm; and stabl e response after 15-30 min. Ammonia interfered in hydrazines detection through a product ion with the same drift time as that for MMH and HZ . Acetone reagent gas was replaced with 5-nonanone to alter drift time s of product ions and separate ammonia from MMH and HZ. Patterns in mo bility spectra, ion identifications from mass spectra, and fragmentati on cross-sections from collisional-induced dissociations suggest that drift times are governed by ion-cluster equilibria in the drift region of the mobility spectrometer. Practical aspects including calibration , stability, and reproducibility are reported from the use of a hand-h eld mobility spectrometer on the space shuttle Atlantis during mission STS-37.