Assessment of on-line and off-line instruments for the measurement of polyfunctional oxygenated organic volatile compounds (OVOCs) under controlled conditions
Authors: Munoz Amalia , Rodenas Mila , Brenan Alexander , Colmenar Inmaculada , Dellen Julian , Gratien Aline , Gomez Tatiana , Kari Eetu , Michoud Vicent , Mutzel Anke , Newland Mike , Reimer David , Rickard Andrew , Seakins Paul , Shaw Marvin , Speak Thomas , Tillmann Ralf , Vera Teresa , Virtanen Annele , Wedel Sergej 
Published: March 2020

&lt;p&gt;The photooxidation and ozonolysis of a wide range of anthropogenic and biogenic compounds results in the formation of polyfunctional oxygenated organic volatile compounds (OVOCs), which are ubiquitous intermediates and important source of radicals, as well as a significant contributor to the organic fraction of aerosol, playing an important role in the air quality and in the health.&lt;/p&gt;&lt;p&gt;With the aim of ensuring a good quality of the measurements, an intercomparison campaign on instruments and techniques to measure OVOCs was held at the EUPHORE atmosphere simulation chamber (Valencia, Spain), allowing the simultaneous sampling from the same air mixture under controlled conditions and facilitating the characterization of the instrumental performance. This intercomparison is part of the activities within the EUROCHAMP-2020 project (www.eurochamp.org) and is aligned with the ACTRIS objectives. &amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;On-line and off-line techniques were employed. These comprised different approaches of mass spectrometers and optical devices as on-line systems and a suite of commercial and non-commercial cartridges as off-line. Some of the experiments were also modeled. The intercomparison included three types of scenarios, the two later simulating typical urban and semi-urban conditions: 1. Synthetic mixture of carbonyls, 2. Products from photooxidations of biogenic and anthropogenic VOCs and 3. Products from ozonolysis of biogenic VOC and monoterpenes, under different relative humidity conditions.&lt;/p&gt;&lt;p&gt;This work represents a step forward in the evaluation and conclusions of the data obtained. An overall good agreement was found among the techniques with good correlations, especially in the synthetic mixtures, as expected, while these parameters worsen under more realistic conditions with complex gas samples. Regarding off-line techniques, good practices on sample storage and use are discussed. Advanced analysis using clusters was also applied to group instruments with similar behaviour, indicating similar performance among the on-line instruments although partitions revealed certain discrepancies. The role of the gas mixture, the calibration set-up and the humidity conditions are discussed in this work.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;This project/work has received funding from the European Union&amp;#8217;s Horizon 2020 research and innovation programme through the EUROCHAMP-2020 Infrastructure Activity under grant agreement No 730997. CAPOX from the Spanish R+D program, Ref RTU2018-097768-B-C21 and PROMETEO from the GVA excellence R&amp;D program, Ref PROMETEO (2019/110) are acknowledged. F. CEAM is partly supported by Generalitat Valenciana.&lt;/p&gt;