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| Titel |
PTR-QMS versus PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013 |
| VerfasserIn |
C. Warneke, P. Veres, S. M. Murphy, J. Soltis, R. A. Field, M. G. Graus, A. Koss, S.-M. Li, R. Li, B. Yuan, J. M. Roberts, J. A. Gouw |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 1 ; Nr. 8, no. 1 (2015-01-26), S.411-420 |
| Datensatznummer |
250116063
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| Publikation (Nr.) |
 copernicus.org/amt-8-411-2015.pdf |
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| Zusammenfassung |
| Here we compare volatile organic compound (VOC) measurements using a standard
proton-transfer-reaction quadrupole mass spectrometer (PTR-QMS) with a new
proton-transfer-reaction time of flight mass spectrometer (PTR-TOF) during
the Uintah Basin Winter Ozone Study 2013 (UBWOS2013) field experiment in an
oil and gas field in the Uintah Basin, Utah. The PTR-QMS uses a quadrupole,
which is a mass filter that lets one mass to charge ratio pass at a time,
whereas the PTR-TOF uses a time of flight mass spectrometer, which takes full
mass spectra with typical 0.1 s–1 min integrated acquisition times. The
sensitivity of the PTR-QMS in units of counts per ppbv (parts per billion by volume) is about a factor of
10–35 times larger than the PTR-TOF, when only one VOC is measured. The
sensitivity of the PTR-TOF is mass dependent because of the mass
discrimination caused by the sampling duty cycle in the
orthogonal-acceleration region of the TOF. For example, the PTR-QMS on mass
33 (methanol) is 35 times more sensitive than the PTR-TOF and for masses
above 120 amu less than 10 times more. If more than 10–35 compounds are
measured with PTR-QMS, the sampling time per ion decreases and the PTR-TOF
has higher signals per unit measuring time for most masses. For UBWOS2013 the
PTR-QMS measured 34 masses in 37 s and on that timescale the PTR-TOF is
more sensitive for all masses. The high mass resolution of the TOF allows for
the measurements of compounds that cannot be separately detected with the
PTR-QMS, such as oxidation products from alkanes and cycloalkanes emitted by
oil and gas extraction. PTR-TOF masses do not have to be preselected,
allowing for identification of unanticipated compounds. The measured mixing
ratios of the two instruments agreed very well (R2 ≥ 0.92 and within
20%) for all compounds and masses monitored with the PTR-QMS. |
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