Polar organic compounds (POCs) are chemicals with polar functional groups in their structure. The functional groups make the compounds hydrophilic and less prone to partition with biota. However, the knowledge of their fate is limited due to difficulties associated with their measurements. Although, the persistence of POCs in the environment is generally low, they are considered to be semi-persistent compounds due to their continuous introduction to the environment via wastewater. Studies have shown that complex mixtures of POCs of different classes may have synergistic toxic effects on biota at environmental concentration levels. Therefore, it is important to develop analytical methods in order to establish the occurrence and fate of POCs in aquatic environments. In Study I, a positive correlation between the sorption of a novel poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC) material and the theoretical logarithmic dissociation partition coefficient (Log D) for seven POCs was observed. The PEVAC material showed an enhanced sorption of the POCs compared to the silicone material. Study II, demonstrated that the PEVAC sampler assess the freely dissolved concentration of POCs in aquatic environments. The results showed that the PEVAC polymer is an attractive alternative to silicone for mimicing the biological uptake of POCs in aquatic environments. Additionally, Study II showed that total extraction is appropriate for determination of the freely dissolved concentration of uncharged POCs with Log KOW < 2.67 in natural water. In study III, a novel bag-solid phase extraction (bag-SPE) technique was compared to a conventional SPE-technique. Despite that the extraction efficiencies for POCs in wastewater were lower using the bag-SPE method, the two methods showed similar detection limits due to the lower ion-suppression experienced with the bag-SPE. In study IV the bag-SPE method was further developed with the aim of lowering the detection limits for POCs. Detection limits (LOD) below 13 ng/L showed that the bag-SPE method was suitable for determination of POCs in surface sea water. / This research was financially supported by European Union (European Commission, FP6 Contract No. 003956) “Novel Methods for Integrated Risk Assessment of Cumulative Stressors in the Environment” (NoMiracle) and by the Swedish research council Formas.