As an assignment from the Swedish Environmental Protection Agency, the Swedish Research Institute (IVL) has performed measurements of 2,4,6-tri-tert butylphenol and Short Chain Chlorinated Paraffins (SCCPs) in sediments. The study has been carried out based on Annex 2: Strategy for a base line one off survey for SCCPs (Agenda Item 7, ASMO 06/7/2-E-(L)) and from the OSPAR meeting, Meeting of the environmental assessment and monitoring committee (ASMO, Hamburg: 24-28 April 2006). These measurements is a Swedish contribution to an “OSPAR base line one off survey” with sampling and analysis of SCCPs and 2,4,6-tri-tert-butylphenol in sediments collected in Göta Älv estuary on the Swedish west coast. This sampling was planned according to the advice to the design of the one-off surveys of chemicals identified for priority actions by ICES 2005 according to points 1-3: 1. The purpose of the one-off surveys is to gain a rapid overview of the occurrence of certain priority chemicals in the marine environment. This could be achieved already by small scale surveys through a limited number of samples, using one sampling type only (for example sediments) and concentrating sampling in estuaries; 2. A minimum of five samples per Contracting Party was required for a focused survey comprising one sample for reference, two samples from polluted areas and two samples from less polluted areas; 3. Sampling could be carried out for the purpose of several one-off surveys for different substances if provided in quantities of 50-500 g of the top centimetres of the sediments. If frozen and kept in a sample bank, the samples could be used at any time when the budget became available for their analysis and for the completion of the survey; This project was carried out in cooperation between IVL and the consultant Marine Monitoring Ltd. Apart from the 2,4,6-tri-tert butylphenol, analysis of 2,4-di-tert-butylphenol and 2,6-di-tert-butylphenol were also included in this study.