Intercomparison of oxygenated volatile organic (OVOC) measurements at the SAPHIR atmosphere simulation chamber

This paper presents the first large scale in-situ intercomparison of oxygenated volatile organic compound (OVOC) measurements. The intercomparison was performed blind with sixteen analytical instruments challenged with measuring atmospherically relevant OVOC species and was conducted at the large (300 m3) simulation chamber, SAPHIR, in Jülich, Germany. The instruments, representing a wide variety of techniques, were challenged with different mixing ratios of OVOCs plus toluene (14 species, C1 to C7) and ozone and water in the approximate range 10-0.6 ppbV. Data will be presented for the entire 1 week study. The SAPHIR chamber proved to be an excellent facility for conducting this experiment. Measurements from individual instruments were compared to mixing ratios calculated from the chamber volume and the known amount of OVOC injected into the chamber. Most instruments and species compared to within factor of two with the calculated values. However, a number of instruments compared much better than this. Some species appeared to be easier to measure than others. For example, acetone compared very well whereas others, such as benzaldehyde, proved to be more difficult.