Time: June 13, 2024 (Thursday) 14:00

Venue: Room 231, New Environmental Building

Inviter: Yitao Pan, Jiayin Dai

Webinar title 1: Comprehensive Assessment of Poly-/Perfluoroalkyl Substances (PFAS) in Contaminated Soil

Speaker: Leo Yeung


Poly- and perfluoroalkyl substances (PFAS) are groups of anthropogenic compounds, and regulations on limiting and/or banning the use of some PFAS have been introduced. To date, more than 5000 PFAS have been registered on the global market. However, only a limited number of PFAS are being monitored in various monitoring programs. The production of "new" PFAS is usually not evaluated in current monitoring programs, which might lead to overlooking their existence in the environment and human exposure. As naturally occurring organofluorine compounds are rare, organofluorine mass balance analysis may be useful as a proxy to estimate overall exposure to PFAS. For soil samples, extraction is usually done with alkaline digestion first, followed by solid-liquid extraction using organic solvents such as methanol. However, a recent study showed that up to 97% of the total PFAS mass was missing if only alkaline methanolic extraction was used. The manuscript authors applied acidic extraction after alkaline methanol extraction to capture cationic and zwitterionic PFAS. In this investigation, AFFF-impacted soil (n=10) collected from three different locations was extracted with sequential basic and acidic methanol and analyzed for PFAS, extractable organofluorine (EOF), total oxidizable precursor assay (TOPA), and PFAS suspects with suspect screening from a database to answer the research questions indicated above. Preliminary results of 5 soil samples showed that at least 60% of the total PFAS31 was accounted for by PFOS. The total PFAS31 only accounted for up to 15% of EOF, and TOPA helped account for up to 15% of the unknown. The amount of EOF between basic and acidic methanol showed that over 70% of EOF was in the basic methanol fraction in 3 out of 5 soil samples, whereas the other two soil samples contained only 30-50% of EOF, indicating that a significant amount of EOF/PFAS remained in the soil if only basic methanol was used. More than 20 PFAS from 7 different classes were additionally identified through suspect screening. Preliminary results suggest that the number of suspects was not missed if alkaline extraction was used; however, the amount of EOF would be underestimated without acidic methanol extraction.

About the speaker:

Leo Yeung is an associate professor at the MTM (Man-Technology-Environment) Research Centre, School of Science and Technology, Örebro University, Sweden. Leo joined the MTM Research Centre as a senior lecturer in 2016 and became an associate professor in 2018. He obtained Bachelor degree from the University of Hong Kong, Master of Philosophy and PhD (Environmental Chemistry - 2009) from City University of Hong Kong under supervision of Dr. Nobuyoshi Yamashita and Prof. Paul Lam. He conducted his post-doctoral training at University of Toronto under supervision of Prof. Scott Mabury. His current research interests are to develop analytical method on measurement of PFAS including replacement products; to apply the organofluorine mass balance approach to understand current PFAS contamination in the environment using combustion ion chromatography; to identify and measure newly identified PFAS in environmental samples using LC-ToF MS and LC-MS/MS spectrometry techniques; and to study the fate and transport of unidentified PFASs in the environment.

Webinar title 2: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) Related to Paper Products and Manufacturing

Speaker: Anna Kärrman


Per- and polyfluoroalkyl substances (PFAS) is a large group extensively used in a broad range of applications and products. Paper products that might contain PFAS includes food packaging (plates, popcorn bags and pizza cartons) and other paper packaging materials such as cartons, containers, and masking paper. Many PFAS are extremely persistent in the environment and the human body and can accumulate over time. The use of PFAS in paper products can be a source for human exposure or end-of-life emissions, and current and historical use of PFAS in paper industries are known to cause environmental emissions. The aim of this presentation is to provide an overview of methodologies and challenges regarding analysis of PFAS by presenting two studies performed on paper products and sediment close to paper industries. Since possible target PFAS are numerous, and analytical standards are partly lacking, the methodologies also cover non-specific assessment, by analysis of fluorine, and oxidative pre-treatment.

About the speaker:

Anna Kärrman, Associate Professor at Örebro University in Sweden, Member of the Swedish Toxicological Board (Toxikologiska rådet), Deputy head of EnForce at Örebro University, Member of editorial board for Kemisk Tidskrift, and previously served as Organizer of research sailing expedition ‘Baltic Sea Expedition’. She has long been dedicated to the field of environmental analytical chemistry and emerging organic pollutants, particularly per- and polyfluoroalkyl substances (PFAS) and microplastics, including their environmental distribution, sources, and human exposure. With extensive research experience in the development of relevant and sensitive methods including non-targeted methodologies to unravel the identity of drivers of toxicity, she has published over 80 SCI articles in authoritative journals such as Environmental Science & Technology, Analytical Chemistry, and Water Research. Her notable contributions have been recognized, with representative works selected as the 20th most cited article in Environmental Science & Technology in 2006. Her H-index is 39, with a total citation count of 4345. As an expert in environmental analytical chemistry, Anna Kärrman has been engaged by the United Nations Environment Programme (UNEP) for multiple training programs worldwide on analyzing environmental pollutants like PFAS and POPs. Moreover, she has spearheaded numerous research projects on emerging contaminants, backed by funding from the Swedish Environmental Protection Agency (Swedish EPA).