Jump to main content
Jump to site search

Issue 1, 2011
Previous Article Next Article

Ion/molecule reactions for detecting ammonia using miniature cylindrical ion trap mass spectrometers

Author affiliations

Abstract

Gaseous ammonia, a common toxic industrial compound, is not detected readily in ion trap mass spectrometers because its molecular ion falls below the low-mass cutoff (∼m/z 40) normally used when examining organic compounds. Instead, reactions of ammonia with halobenzene radical cations were used with internal electron ionization in two cylindrical ion trap miniature mass spectrometers to create a characteristic product ion by which to identify and quantify ammonia. Ammonia showed a linear response over the concentration range studied (parts per million [ppm] to parts per billion [ppb]) with limits of detection of 17 ppm and 220 ppb for experiments involving direct introduction and thermal desorption after pre-concentration, respectively. These values are comparable to ammonia's permissible exposure limit (50 ppm) and odor threshold (5 ppm). Receiver operating characteristic (ROC) curves were used to describe the method sensitivity, the probability of true positives, and the false positive rate for ammonia. A customized reaction scan function was created to select the species available for the ion/molecule reaction and set the amount of time the product ion could be accumulated in the trap. Product ion identity was verified using tandem mass spectrometry. Similar reactions with methylamine, ethylamine and the two nitriles, acetonitrile and benzonitrile, were explored.

Graphical abstract: Ion/molecule reactions for detecting ammonia using miniature cylindrical ion trap mass spectrometers

Back to tab navigation

Supplementary files

Publication details

The article was received on 12 Aug 2010, accepted on 01 Oct 2010 and first published on 25 Oct 2010


Article type: Paper
DOI: 10.1039/C0AN00630K
Citation: Analyst, 2011,136, 120-127
  •   Request permissions

    Ion/molecule reactions for detecting ammonia using miniature cylindrical ion trap mass spectrometers

    J. N. Smith, A. D. Keil, R. J. Noll and R. G. Cooks, Analyst, 2011, 136, 120
    DOI: 10.1039/C0AN00630K

Search articles by author

Spotlight

Advertisements