This International Standard specifies a method for the determination of selected polybrominated diphenylethers (PBDE) (Table 1) in sediment and sludge using gas chromatography/mass spectrometry (GC MS) in the electron impact (EI) or negative ion chemical ionisation (NCI) mode. When applying GC EI MS, the method is applicable to samples containing 0,05 µg/kg to 25 µg/kg of tetra- to octabromo congeners and 0,3 µg/kg to 100 µg/kg of decabromo diphenylether (BDE 209), respectively. Approximately ten times lower concentrations can be quantified when using GC NCI MS. The risk of misinterpretation of interfering substances is smaller with EI due to its higher specifity. It is possible to analyse as well other brominated diphenylethers according to this International Standard but its applicability shall be verified in each case.