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Intercomparison of Oxygenated Volatile Organic Compound (OVOC) Measurements

ACCENT QA Integration Task

Oxygenated volatile organic compounds (OVOC) are important players in tropospheric photochemistry. The are emitted from anthropogenic and natural sources but also formed in the photochemical transformation of other VOC.

Within this activity a workshop was held at the Research Centre Jülich, Germany, October 11-12, 2004, to prepare the intercomparison experiment at the atmosphere simulation chamber SAPHIR.

In the period October - December 2004 intensive preparatory work was carried out to ensure a successful intercomparison experiment. Various tests concerning the stability of mixtures of OVOC were done as well as tests introducing those mixtures into the SAPHIR chamber. Additionally, hardware components such as manifolds, inlet lines, and gas supply for the different instruments were set up and tested.

The intercomparison experiment was carried out January 17-28, 2005. 12 groups participated in this intercomparison with a variety of different instruments covering the whole range from standard techniques to newly developed methods. The intercomparison was conducted as a formal "blind" intercomparison. The referee is Eric Apel, NCAR, Boulder, CO, USA.

List of compounds intercompared in this experiment:
formaldehyde, acetaldehyde, butanal, hexanal, methanol, ethanol, 1-propanol, 1 butanol, methacrolein, methyl vinyl ketone, acetic acid methyl ester, acetone, benzaldehyde, 2-methyl-3-buten-2-ol
n-butane and toluene were added as tracers for dilution processes in SAPHIR and as reference compounds for gas chromatography.

According to our experience with previous intercomparison experiments the results of such an intercomparison lead to a substantial improvement of the measurement techniques.

The results of the ACCENT OVOC intercomparison activity will

  • improve the methods for the measurement of OVOC in the atmosphere, foster analytical training,
  • enhance the transfer of knowledge through scientific and technical communication among the participants,
  • demonstrate the importance of regular proficiency tests to stay abreast of advancing technology.