Synthetic chemicals, which are designed for a specific purpose, often have undesirable side effects when released into the environment. A group of such compounds known as endocrine disrupting chemicals (EDCs), can affect the normal growth and development of wildlife. This investigation focuses on two EDCs: nonylphenol polyethoxylates (NPEOx) and nonylphenol (NP). As a result of their application, it is possible for these compounds to enter the aqueous environment through discharge of sewage effluent. Methods for the extraction and analysis of the selected EDCs from sewage effluent and loch sediment were developed. Solid phase and liquid/liquid solvent extraction were used with aqueous samples for the extraction of NPEOx and NP respectively. Solid specimens required the use of automated sohxtherm extraction. LC-MS was utilised in the analysis of NPEOx, whilst GC-MS was applied to the analysis of NP. A survey of six wastewater treatment works (wwtw) was carried out in order to monitor the concentrations and behaviour of NPEOx and NP. NPEOx was found in all works with a range of < 1µg/l to 31µg/l.