This Technical Specification specifies a method for the determination of nonylphenols (NP), nonylphenol-monoethoxylates (NP1EO) and nonylphenol-diethoxylates (NP2EO) in sludge, treated biowaste and soil using GC-MS. For sludge a limit of detection of 0,1 mg/kg and for soil and treated biowaste 0,02 mg/kg (expressed as dry matter) may be achieved. Lower limits of detection may be achieved by concentrating the extract by solvent evaporation. NOTE 4-tert-octylphenol can also be analysed with this method.