Örebro University, Sweden

Heidelore ("Heidi") Fiedler is a professor of chemistry and joined the MTM Research Centre in July 2015. She brings 15 years of professional experience from the United Nations Environment Programme (UNEP) ...

where she was responsible for the Science and Risk Team. Prior to the UNEP assignment she worked as a senior researcher at the University of Bayreuth (Germany) and the Bavarian Institute for Waste Research (BIfA, Augsburg, Germany).



PFOS monitoring in water under the Stockholm Convention’s Global Monitoring Plan

Heidelore Fiedler1

1Örebro University, School of Science and Technology, MTM Research Centre, SE-701 82 Örebro, Sweden, E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Perfluorooctane sulfonic acid (PFOS), its salts and perfluorooctane sulfonyl fluoride was listed in the annex B of the Convention at the fourth meeting of the Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants (POPs) in 20091.  With the listing of new POPs, the need for updating the guidance document for the “Global Monitoring Plan of POPs” (GMP) became evident2.  A small working group was set-up to develop the guidance for PFOS monitoring.  As a first result, and since water is the main transport medium for PFOS in the environment, surface water was added as a core matrix in the guidance document for the GMP for PFOS (but not for the other 26 POPs listed until 2015) and the criteria for future PFOS monitoring in water3.  Further, a standard operational procedure document was prepared to assist in the sampling of water for the analysis of PFOS (or PFAS)4.  Since 2017, the sampling of surface water is underway in 22 countries in the framework of four UN Environment-coordinated regional projects to support the Global Monitoring Plan on POPs using the recommended direct sampling approach. 

In brief, surface water samples were collected (1 L HPDE bottles) from up to 22 countries in Africa, Asia, Pacific Islands and Latin America/Caribbean regions with one sampling location per country and 4-times per year.  Water samples are analysed in the MTM Research Centre’s PFAS laboratory.  Where national capacity is available, a second sample is taken and analysed in the on-site laboratory.

The sampling protocol and the chemical analysis did show that the recommended approach works well.  After having generated the first results on L- and br-PFOS, we have amended the analytes by the two PFAS that are presently under consideration for listing in the Stockholm Convention, namely perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS).  The water samples are clean using solid phase extraction and separation and quantification of PFAS was performed on liquid chromatograph coupled to a tandem mass spectrometer.  It shall be noted that comparison with other data in the published literature is often difficult since the procedures do not reveal which PFAS have been quantified (linear or total PFOS, etc.).

So far, 50 water samples from all regions have been analyzed:  L- and br-PFOS were found in all samples with a maximum of 4.39 ng/L for total PFOS (2.89 ng/L for L-PFOS and 1.50 ng/L for br-PFOS) and the possible new POPs – PFOA and PFHxS – were detected in similar range.

The work was funded by the Global Environment Facility through a grant from UN Environment to Örebro University.


1 UNEP, Decision SC-4/17: Listing of perfluorooctane sulfonic acid (PFOS), its salts and perfluorooctane sulfonyl fluoride in annex B. 2009, United Nations Environment Programme: New York, NY, USA.

2 UNEP, Guidance on the Global Monitoring Plan for Persistent Organic Pollutants, UNEP, 2015. p. 168

3 Weiss, J., et al., PFAS analysis in water for the Global Monitoring Plan of the Stockholm Convention Set-up and guidelines for monitoring, in United Nations Environment Programme (UNEP) Division of Technology, Industry and Economics, Geneva. 2015.

4 UN Environment, Global Monitoring Plan on Persistent Organic Pollutants:  Standard Operational Procedure for the Sampling of Water as a Core Matrix in the UNEP/GEF GMP2 Projects for the Analysis of PFOS, Heidelore Fiedler and Leo Yeung, Örebro University, Editor. 2017, UN Environment, Environment and Health Branch: Geneva, Switzerland. p. 11.