Ground-based intercomparison of two isoprene measurement techniques

Abstract

Abstract. An informal intercomparison of two isoprene (C 5 H 8 ) 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 wellestablished 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.

Organic Trace Gases in the Atmosphere: An Overview

“…multidimensional gas chromatography [62] ) or at higher frequency with chemical ionization mass spectrometry (CIMS) through use of proton transfer reactions, [63][64][65] or by other chemical ionization techniques. [66,67] Further measurement systems have developed high precision to enable δ 13 C isotopic ratios to be determined in organics at mixing ratios below ppbv levels, [68] while various high-frequency methods have been developed to measure emission fluxes directly. [69,70] With the arrival of this new generation of measurement systems, more species and timescales are accessible and a new golden age of discovery for field measurement has begun.…”