Per- and polyfluoroalkyl substances (PFAS) are a group of highly fluorinated compounds which comprises of more than 4700 substances. A smaller number of those substances is rou-tinely measured, usually the short (C4-C7) and long chain PFAS (>C7). Detection of PFAS in different water matrices including wet precipitation have been done previously in a limited number of studies, including ultra-short chain compounds (C1-C3). Ultra-short chain com-pounds have however not been investigated to a larger extent. In this study, twelve rainwater samples from Råö have been analysed, each representing a composite sample of one month. Long (C8-C18), short as well as ultra-short chain PFAS have been included in the analysis. Long and short chain compounds were analysed with ultra-performance liquid chromatography tan-dem mass spectrometer (UPLC-MS/MS) and ultra-short chain compounds with ultra-perfor-mance convergence chromatography tandem spectrometer (UPCC-MS/MS). Long and short-chain PFAS had a total detectable concentration of 5.1-110 ng/L. A seasonal trend was also studied, which showed a significant difference when performing a Kruskal Wallis test in meas-ured total mean long and short chain PFAS concentration. Dunnet´s test indicated a significant difference between all the seasons. Highest concentrations were measured during summer and lowest during winter. Ultra-short chain compounds analysed by UPCC MS/MS had a total concentration between 16-410 ng/L. No significant difference in total ultra-short PFAS mean concentration could be seen between different seasons using a Kruskal Wallis test. The total PFAS concentration in the rain samples ranged from 28 to 540 ng/L, where ultra-short chain PFAS contributed to 58-92 % of the total concentration. Which makes them an important group to include in future measurements of PFAS in water samples and especially in rainwater sam-ples.

PFAS are anthropogenic substances used in many different industrial operations and products because of their unique properties. Due to their negative impact on human health and environmental bioaccumulative characteristics different authorities have addressed the issue. In Sweden the limit is4 ng/L for four different PFAS in drinking water. Another risk to human health is elevated concentrations of toxic elements, causing Sweden to include them in the drinking water regulations withlimits such as 5 µg/L for arsenic, 25 µg/L for chromium and 5 µg/L for lead.This study is a continuation of an investigation for PFAS remediation in contaminated water by sorption to pine and spruce bark. The earlier study was a laboratory scale and implied that pine and spruce have some sorption capacity for long-chain PFAS. In this study pine and spruce bark were used as sorbent at an industrial site. The analysis was performed by weak-anion exchange extraction followed bysupercritical fluid chromatography coupled with a tandem mass spectrometer (SFC-MS/MS) and liquid chromatography coupled with tandem mass spectrometer (LC-MS/MS) for instrumental analyses of target ultra-short-chain PFAS, short- and long chain PFAS and branched PFOS isomers. An elemental analysis was executed with inductively coupled plasma mass spectrometry. The obtained results indicated removal for certain long-chain PFAS, potential for sorption of a specific ultra-short-chain PFAS and the elemental analysis implied some reduction of the chromium concentrations.