PTR Intercomparison in CABauw (PICAB)

Last September, 18th – 28th, our research group participated in the PTR Intercomparison in CABauw (PICAB) campaign held in the Netherlands together with 10 other institutes. Organized within the European Research Infrastructure for the Observation of Aerosol, Clouds, and Trace gases (ACTRIS), the event gathered not less than 11 mass spectrometers (PTR-MS) dedicated to measure the concentrations of Volatile Organic Compounds (VOCs) present in the near-surface atmosphere.

With such an impressive panel of instruments, our main goal was to evaluate how well the instruments were measuring and how the obtained concentrations of volatiles were comparable among the instruments, knowing that they were all measuring the same air parcel.

 Photo: Lauriane Quéléver

In practice, we measured the outside air from the same sampling line located at the bottom of the CESAR (Cabauw Experimental Site for Atmospheric Research) meteorological tower (seen on the picture). Additionally, every day we performed calibrations using a gas mixture of known chemical composition and concentrations with two different types of carrier gas (synthetic air or pure nitrogen) at wet and dry conditions.

As a result, we saw that all the instruments showed similar VOC concentrations, which itself was a great success!  Furthermore, using data from 11 PTR-MS, including two with ‘very-high mass resolution’, we can confirm the previous studies done on VOC signature of agricultural areas as measured at the CESAR site. The work is further continuing with the redaction of a Standard Operation Procedure that will describe in detail how to install the instrument and set its parameters highlighting the best practices in PTR-MS measurements.

Being rather a novice in the ‘PTR world’, I definitely learned a lot about the PTR-TOF-8000 (Ionicon Analytik) that we have in Helsinki, but also from the other types of PTR-MS such as Qi-TOF, PTR-TOF, PTR-Quad or the newer PTR3 and VOCUS ’long-TOFs’.

More information about the projects below:

ACTRIS Research Infrastructure

CESAR Observatory

The Royal Netherlands Meteorological Institute (KNMI)