Preprints
https://doi.org/10.5194/egusphere-2026-3918
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-3918
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
30 Jul 2026
| 30 Jul 2026
Status: this preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
Harmonizing measurements of oxidative potential of PM: an interlaboratory comparison of the ascorbic acid assay
Abstract. Oxidative potential (OP) of atmospheric particulate matter (PM) is a metric of increasing scientific interest because it potentially links chemical particle properties to particle health effects. OP has been recently introduced as a recommended monitoring metric in the European Air Quality Directive. However, inconsistent protocols in the existing literature make it difficult to compare results across studies. Following a 2023 inter-laboratory comparison that focused on PM OP measured using the dithiothreitol (DTT) assay, this paper presents the findings and lessons learnt from a second inter-laboratory study focused on the ascorbic acid assay (OP-AA). In this study, twenty-six laboratories worldwide quantified OP of four PM filter samples and of one chemical compound to evaluate the entire analytical chain, including the extraction step, using a simplified OP-AA protocol. While most laboratories produced repeatable internal results when applying the simplified protocol, significant discrepancies between participants highlight the need for each laboratory to carefully evaluate deviations from the simplified OP-AA protocol. Over half of the 26 participants achieved satisfactory results, suggesting that the protocol is suitable for large-scale implementation. Beyond assessing performance, this work investigates technical, analytical, and mathematical refinements to measurement protocols. Building on the first DTT assay study, this second inter-laboratory comparison represents a significant step toward harmonizing OP assays, and provides specific recommendations to ensure consistent future measurements, ready to be applied in the new air quality directive EU 2024/2881.
How to cite. Marsal, A., Cavalli, F., Di Antonio, E., Houdier, S., Dominutti, P., Darfeuil, S., Jaffrezo, J.-L., Sauvage, S., Putaud, J.-P., Mudway, I. S., Nenes, A., Bougiatioti, A., Mihalopoulos, N., Prévôt, A. S. H., Paraskevopoulou, D., Kušan, A. C., Frka, S., Kroflič, A., Delić, A., Tariba Lovaković, B., Jurič, A., Molina, C., Contini, D., Guascito, M. R., Lintz, M., Rousset, D., Herrmann, H., Souza, E. J. d. S., Ledoux, F., Fadel, M., Yu, H., Yu, J., Baeza Romero, M. T., Cerrato-Alvarez, M., van Os, M. F., Delaval, M. N., Mena Cabrera, Y. M., Trieu, N., Evans, G., Galindo, N., Gómez-Sanchez, N., Hlaváčková, H., Mikuška, P., Kadam, S., Shahpoury, P., López-Mahía, P., Moreda-Piñeiro, J., Cheung, R. K. Y., Kalberer, M., Introna, M., Steimer, S. S., Lin, Z., Paulson, S. E., Iram, S., Stevanovic, S., Audoux, T., Alleman, L. Y., Liu, J., Fang, T., Subramanian, P. S. G., Verma, V., Petäjä, T., Querol, X., Hoek, G., Harrison, R. M., and Uzu, G.: Harmonizing measurements of oxidative potential of PM: an interlaboratory comparison of the ascorbic acid assay, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-3918, 2026.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Measurement Techniques.
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Anouk Marsal
CORRESPONDING AUTHOR
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Fabrizia Cavalli
European Commission, Joint Research Centre (JRC), Ispra, Italy
Elise Di Antonio
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Stephan Houdier
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Pamela Dominutti
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Sophie Darfeuil
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Jean-Luc Jaffrezo
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Stéphane Sauvage
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Jean-Philippe Putaud
European Commission, Joint Research Centre (JRC), Ispra, Italy
Ian S. Mudway
MRC Centre for Environment and Health, Environmental Research Group, Imperial College London, 86 Wood Lane, London, W12 0BZ, UK
Athanasios Nenes
Center for the Study of Air Quality and Climate Change, Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, 26504, Greece
Laboratory of Atmospheric Processes and their Impacts, Institute of Environmental Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Aikaterini Bougiatioti
Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Lofos Koufou, P. Penteli, Athens, 15236, Greece
Nikolaos Mihalopoulos
Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Lofos Koufou, P. Penteli, Athens, 15236, Greece
Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Heraklion, 71003, Greece
André S. H. Prévôt
Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
Despina Paraskevopoulou
Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Lofos Koufou, P. Penteli, Athens, 15236, Greece
Ana Cvitešić Kušan
Division for Marine and Environmental Research, Ruđer Bošković Institute, 10000, Zagreb, Croatia
Sanja Frka
Division for Marine and Environmental Research, Ruđer Bošković Institute, 10000, Zagreb, Croatia
Ana Kroflič
Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, 1000 Ljubljana, Slovenia
School of Environmental Sciences, University of Nova Gorica, 5271 Vipava, Slovenia
Ajda Delić
Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, 1000 Ljubljana, Slovenia
University of Maribor, Faculty of Chemistry and Chemical Technology, Smetanova ulica 17, 2000 Maribor, Slovenia
Blanka Tariba Lovaković
Division of Toxicology, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia
Andreja Jurič
Division of Toxicology, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia
Carolina Molina
Center for the Study of Air Quality and Climate Change, Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, 26504, Greece
Daniele Contini
Institute of Atmospheric Sciences and Climate, ISAC-CNR, Str. Prv. Lecce-Monteroni km 1.2, 73100 Lecce, Italy
Maria Rachele Guascito
Institute of Atmospheric Sciences and Climate, ISAC-CNR, Str. Prv. Lecce-Monteroni km 1.2, 73100 Lecce, Italy
University of Salento, Department of Biological and Environmental Sciences and Technologies, Via per Arnesano, 73100 Lecce, Italy
Mathilde Lintz
Department of Pollutant Metrology, Institut National de Recherche et de Sécurité (INRS), 54500 Vandœuvre-lès-Nancy, France
Davy Rousset
Department of Pollutant Metrology, Institut National de Recherche et de Sécurité (INRS), 54500 Vandœuvre-lès-Nancy, France
Hartmut Herrmann
Atmospheric Chemistry Department (ACD), Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Germany
Eduardo J. d. S. Souza
Atmospheric Chemistry Department (ACD), Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Germany
Frédéric Ledoux
Unité de Chimie Environnementale et Interactions sur le vivant (UCEIV), UR4492, Université du Littoral Côte d’Opale, 59140, Dunkerque, France
Marc Fadel
Unité de Chimie Environnementale et Interactions sur le vivant (UCEIV), UR4492, Université du Littoral Côte d’Opale, 59140, Dunkerque, France
Haoran Yu
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Canada
Jianzhen Yu
The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
Maria Teresa Baeza Romero
Escuela de Ingeniería Industrial y Aeroespacial de Toledo, Universidad de Castilla-la-Mancha, Toledo 45004, Spain
Maria Cerrato-Alvarez
Escuela de Ingeniería Industrial y Aeroespacial de Toledo, Universidad de Castilla-la-Mancha, Toledo 45004, Spain
now at: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcala, 28871, Alcalá de Henares (Madrid), Spain
Marloes F. van Os
Netherlands Organization for Applied Scientific Research (TNO), Princetonlaan 8, 3584 CB Utrecht, Netherlands
Mathilde N. Delaval
Comprehensive Molecular Analytics (CMA), Helmholtz Zentrum München, Neuherberg, Germany
Yamaris Mercedes Mena Cabrera
Comprehensive Molecular Analytics (CMA), Helmholtz Zentrum München, Neuherberg, Germany
Nicole Trieu
Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, Toronto, M5S 3E5, Canada
Greg Evans
Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, Toronto, M5S 3E5, Canada
Nuria Galindo
Atmospheric Pollution Laboratory (LCA), Department of Applied Physics, Miguel Hernández University, Avda. de la Universidad S/N, Elche 03202, Spain
Noelia Gómez-Sanchez
Atmospheric Pollution Laboratory (LCA), Department of Applied Physics, Miguel Hernández University, Avda. de la Universidad S/N, Elche 03202, Spain
Hana Hlaváčková
Department of Environmental Analytical Chemistry, Institute of Analytical Chemistry, Czech Academy of Sciences, Veveří 97, 60200 Brno, Czech Republic
Pavel Mikuška
Department of Environmental Analytical Chemistry, Institute of Analytical Chemistry, Czech Academy of Sciences, Veveří 97, 60200 Brno, Czech Republic
Shrutika Kadam
Environmental and Life Sciences, Trent University, Peterborough, Canada
Pourya Shahpoury
Environmental and Life Sciences, Trent University, Peterborough, Canada
Purificación López-Mahía
University of A Coruña. Grupo Química Analítica Aplicada (QANAP), University Institute of Research in Environmental Studies (IUMA), Center for Technological Innovation in Construction and Civil Engineering Environmental Studies (IUMA), Center for Technological Innovation in Construction and Civil Engineering Spain
Jorge Moreda-Piñeiro
University of A Coruña. Grupo Química Analítica Aplicada (QANAP), University Institute of Research in Environmental Studies (IUMA), Center for Technological Innovation in Construction and Civil Engineering Environmental Studies (IUMA), Center for Technological Innovation in Construction and Civil Engineering Spain
Rico K. Y. Cheung
Department of Environmental Sciences, University of Basel, 4056 Basel, Switzerland
Markus Kalberer
Department of Environmental Sciences, University of Basel, 4056 Basel, Switzerland
Micol Introna
Department of Environmental Science, Stockholm University, Stockholm, 11418, Sweden
Sarah S. Steimer
Department of Environmental Science, Stockholm University, Stockholm, 11418, Sweden
Bolin Centre for Climate Research, Stockholm, 11418, Sweden
Zhuoying Lin
Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, CA 90095, United States
Suzanne E. Paulson
Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, CA 90095, United States
Saima Iram
School of Engineering, Deakin University, Geelong, 3216 Victoria, Australia
Svetlana Stevanovic
School of Engineering, Deakin University, Geelong, 3216 Victoria, Australia
Thomas Audoux
IMT Nord Europe, Institut Mines-Télécom, Univ. Lille, Centre for Energy and Environment, 59000 Lille, France
Laurent Y. Alleman
IMT Nord Europe, Institut Mines-Télécom, Univ. Lille, Centre for Energy and Environment, 59000 Lille, France
Jianing Liu
Thrust of Sustainable Energy and Environment, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, 511400, China
Ting Fang
Thrust of Sustainable Energy and Environment, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, 511400, China
Thrust of Earth, Ocean, and Atmospheric Sciences, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, 511400, China
P. S. Ganesh Subramanian
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801, United States
Vishal Verma
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801, United States
Tuukka Petäjä
Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki 00014, Finland
Xavier Querol
Institute of Environmental Assessment and Water Research (IDAEA-CSIC), 08034 Barcelona, Spain
Gerard Hoek
Institute for Risk Assessment Sciences, Utrecht University, Utrecht, 3584CM, the Netherlands
Roy M. Harrison
Division of Environmental Health and Risk Management, School of Geography, Earth and Environmental Sciences, Edgbaston, Birmingham, B15 2TT, UK
University Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE (UMR 5001), 38000 Grenoble, France
Short summary
This collaborative work from 26 worldwide laboratories assessed the measurement of atmospheric particles' oxidative potential (OP) using a common protocol. OP is a metric designed to inform on particles’ harmful effects. Over half of the laboratories obtained satisfactory results, and some critical steps such as liquid handling and OP mathematical determination were identified. Recommendations for future measurements and interlaboratory comparisons are also provided.
This collaborative work from 26 worldwide laboratories assessed the measurement of atmospheric...