<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">C Warneke</style></author><author><style face="normal" font="default" size="100%">Veres, P.</style></author><author><style face="normal" font="default" size="100%">Murphy, S. M.</style></author><author><style face="normal" font="default" size="100%">Soltis, J.</style></author><author><style face="normal" font="default" size="100%">Field, R. A.</style></author><author><style face="normal" font="default" size="100%">Graus, M. G.</style></author><author><style face="normal" font="default" size="100%">Koss, A.</style></author><author><style face="normal" font="default" size="100%">Li, S. -M.</style></author><author><style face="normal" font="default" size="100%">Li, R.</style></author><author><style face="normal" font="default" size="100%">Yuan, B.</style></author><author><style face="normal" font="default" size="100%">Roberts, J. M.</style></author><author><style face="normal" font="default" size="100%">de Gouw, J. A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">PTR-QMS versus PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013</style></title><secondary-title><style face="normal" font="default" size="100%">ATMOSPHERIC MEASUREMENT TECHNIQUES</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2015</style></year></dates><number><style face="normal" font="default" size="100%">1</style></number><volume><style face="normal" font="default" size="100%">8</style></volume><pages><style face="normal" font="default" size="100%">411-420</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">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 &amp;gt;= 0.92 and within 20 %) for all compounds and masses monitored with the PTR-QMS.</style></abstract></record></records></xml>