ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-3-67-2003 Ground-based intercomparison of two isoprene measurement techniques Leibrock E. 1 2 4 Huey L. G. 3 Goldan P. D. 1 2 Kuster W. C. 1 2 Williams E. 1 2 Fehsenfeld F. C. 1 2 Aeronomy Laboratory, Environmental Research Laboratories, NOAA, Boulder, Colorado, USA Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA present address: The Boston Consulting Group, Ludwigstraße 21, D–80539 München, Germany 03 02 2003 3 1 67 72 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/3/67/2003/acp-3-67-2003.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/3/67/2003/acp-3-67-2003.pdf

An informal intercomparison of two isoprene (C<sub>5</sub>H<sub>8</sub>) measurement techniques was carried out during Fall of 1998 at a field site located approximately 3 km west of Boulder, Colorado, USA. A new chemical ionization mass spectrometric technique (CIMS) was compared to a well-established gas chromatographic technique (GC). The CIMS technique utilized benzene cation chemistry to ionize isoprene. The isoprene levels measured by the CIMS were often larger than those obtained with the GC. The results indicate that the CIMS technique suffered from an anthropogenic interference associated with air masses from the Denver, CO metropolitan area as well as an additional interference occurring in clean conditions. However, the CIMS technique is also demonstrated to be sensitive and fast. Especially after introduction of a tandem mass spectrometric technique, it is therefore a candidate for isoprene measurements in remote environments near isoprene sources.