PTR-QMS versus PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013

Details

• Journal Title:
  Atmospheric Measurement Techniques
• Personal Author:
  Warneke, C. ; Veres, P. ; Murphy, S. M. ; Soltis, J. ; Field, R. A. ; Graus, M. G. ; Koss, A. ; Li, S.-M. ; Li, R. ; Yuan, B. ; Roberts, J. M. ; de Gouw, J. A.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory)
• Description:
  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 (R-2 >= 0.92 and within 20 %) for all compounds and masses monitored with the PTR-QMS.
• Source:
  Atmospheric Measurement Techniques, 8(1), 411-420.
• DOI:
  https://doi.org/10.5194/amt-8-411-2015
• Document Type:
  Journal Article
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:4affe94f3a134f65a4a399d41fa4f193b3f1545fea3b9ab56487ad8aa1f7b262a5d8688db8c681fd799dedec4df852a527db416b75e58de9905e4273bb623464
• Download URL:
  https://repository.library.noaa.gov/view/noaa/21923/noaa_21923_DS1.pdf
• File Type:
  [PDF - 9.43 MB ]