Polycyclic aromatic hydrocarbons (PAHs) are a group of both naturally occurring and man-made chemicals which exist in over 100 different forms. They are most commonly considered a group of 16 which have been chosen as priority pollutants according to the Water Framework Directive (WFD) 2000/60/EC. The main sources of PAHs in the environment are anthropogenic as they are by-products of incomplete combustion, coal gasification and liquification processes, waste incineration, petroleum cracking, and in the production of coke, coal tar pitch, carbon black, and asphalt. PAHs may also be released into marine environments via sewage, industrial wastewater, road runoff, street dust, and through oil spills and ship traffic due to their presence in un-combusted petroleum. While an efficient wastewater treatment process is said to remove 90 – 95 % of pollutants, it is important to ensure that waste water treatment plant (WWTP) outflow is not contaminating receiving water bodies, making the monitoring of WWTP effluent very important. Effluent samples have been collected from both a secondary and a tertiary waste water treatment plant over a period of 3 months, and 6 months, respectively, including several weeks of high intensive sampling. Solid phase extraction, (SPE), is used in the sample preparation process with subsequent analysis by gas chromatography (GC) with mass spectrometric detection (MS).