Tropospheric Chemistry: Instruments

Acid CIMS instrument

Acid CIMS instrument.

Acid CIMS (Chemical Ionization Mass Spectrometer)

Principle of the Measurement

Negative ion proton transfer chemical ionization mass spectrometry using acetate ions as reagent ions

Species Measured

  • All carboxylic acids (except acetic acid)
  • All common inorganic acids
  • Isocyanic acid (HNCO)
  • Substituted Phenols

Time Response

10 second (nominal)

Detection Limit

5 - 50 pptv (background limited)


±(20% + det. limit)


custom built

Field Projects

  • FireLab 2009
  • CalNex 2010
  • NACHTT 2011


Jim Roberts

Key Publications

Veres, P., J.M. Roberts, C. Warneke, D. Welsh-Bon, M. Zahniser, S. Herndon, R. Fall, and J. de Gouw, Development of Negative-Ion Proton-Transfer Chemical-Ionization Mass Spectrometry (NI-PT-CIMS) for the Measurement of Gas-Phase Organic Acids in the Atmosphere, Int. J. Mass Spectrom., 274, 48-55, doi:10.1016/j.ijms.2008.04.032, 2008.

Roberts, J.M., P. Veres, C. Warneke, J.A. Neuman, R. Washenfelder, S.S. Brown, M. Baasandorj, J. Burkholder, I.R. Burling, T.J. Johnson, R.J. Yokelson, and J. de Gouw, Measurement of HONO, HNCO, and other inorganic acids by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS): Application to biomass burning emissions, Atmos. Meas. Tech., 3, 981-990, doi:10.5194/amt-3-981-2010, 2010.

Veres, P., J.M. Roberts, I.R. Burling, C. Warneke, J. de Gouw, R.J. Yokelson, Measurements of gas-phase inorganic and organic acids from biomass fires by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), J. Geophys. Res., 115, D23302, doi:10.1029/2010JD014033, 2010.

Roberts, J.M., P.R. Veres, A.K. Cochran, C. Warneke, I.R. Burling, R.J. Yokelson, B. Lerner, J.B. Gilman, W.C. Kuster, R Fall, and J. de Gouw, Isocyanic acid in the atmosphere and its possible link to smoke-related health effects, Proc. Natl. Acad. Sci., 108(22), 8966-8971, doi:10.1073/pnas.1103352108, 2011.