An iodide-adduct high-resolution time-of-flight chemical-ionization mass spectrometer: application to atmospheric inorganic and organic compounds

Environ Sci Technol. 2014 Jun 3;48(11):6309-17. doi: 10.1021/es500362a. Epub 2014 May 21.


A high-resolution time-of-flight chemical-ionization mass spectrometer (HR-ToF-CIMS) using Iodide-adducts has been characterized and deployed in several laboratory and field studies to measure a suite of organic and inorganic atmospheric species. The large negative mass defect of Iodide, combined with soft ionization and the high mass-accuracy (<20 ppm) and mass-resolving power (R>5500) of the time-of-flight mass spectrometer, provides an additional degree of separation and allows for the determination of elemental compositions for the vast majority of detected ions. Laboratory characterization reveals Iodide-adduct ionization generally exhibits increasing sensitivity toward more polar or acidic volatile organic compounds. Simultaneous retrieval of a wide range of mass-to-charge ratios (m/Q from 25 to 625 Th) at a high frequency (>1 Hz) provides a comprehensive view of atmospheric oxidative chemistry, particularly when sampling rapidly evolving plumes from fast moving platforms like an aircraft. We present the sampling protocol, detection limits and observations from the first aircraft deployment for an instrument of this type, which took place aboard the NOAA WP-3D aircraft during the Southeast Nexus (SENEX) 2013 field campaign.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Air Pollutants / analysis
  • Air Pollutants / chemistry*
  • Environmental Monitoring
  • Inorganic Chemicals / analysis
  • Inorganic Chemicals / chemistry*
  • Iodides / chemistry*
  • Limit of Detection
  • Mass Spectrometry / methods*
  • Organic Chemicals / analysis
  • Organic Chemicals / chemistry*


  • Air Pollutants
  • Inorganic Chemicals
  • Iodides
  • Organic Chemicals