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Adaptation of a proton transfer reaction mass spectrometer instrument to employ NO + as reagent ion for the detection of 1,3‐butadiene in the ambient atmosphere
Author(s) -
Knighton W. B.,
Fortner E. C.,
Herndon S. C.,
Wood E. C.,
MiakeLye R. C.
Publication year - 2009
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4249
Subject(s) - chemistry , reagent , ion source , mass spectrometry , ion , ionization , proton , analytical chemistry (journal) , parts per notation , impurity , chemical ionization , chromatography , nuclear physics , physics , organic chemistry
A proton transfer reaction mass spectrometer (PTR‐MS) instrument was adapted to employ NO + as a chemical reagent ion without any hardware changes by switching the reagent ion source gas from water vapor to dry air. Ionization of dry air within the hollow cathode ion source generates a very intense source of NO + with only a minor impurity of NO 2 + . The intensities of the primary NO + reagent ion and the unwanted impurity NO 2 +are controllable and dependent on the operational conditions of the hollow cathode ion source. Ion source tuning parameters are described, which maintain an intense source of NO + while keeping the impurity NO 2 +signal to less than 2% of the total reagent ion intensity. This method is applied to the detection of 1,3‐butadiene. NO + reacts efficiently with 1,3‐butadiene via a charge exchange reaction to produce only the molecular ion, which is detected at m/z 54. Detection sensitivities of the order of 45 pptv for a 1‐s measurement of 1,3‐butadiene are demonstrated. We present the first real‐time on‐line sub parts per billion measurement of 1,3‐butadiene in the ambient atmosphere. The only likely interference is from 1,2‐butadiene. Concurrent measurements of benzene are provided and suggest that the vehicular emissions are the predominant source of 1,3‐butadiene in a suburban Boston area monitoring location. Copyright © 2009 John Wiley & Sons, Ltd.