Photometric determination of cationic detergents. • Photometric determination with bromphenol-blue. • Cationic detergents react with bromophenol blue to form a coloured complex, which is extracted with an organic phase. Reference substance is N-cetyl-N,N,N-trimethylammonium bromide (CTAB: 364.5 g/mol). • Type: standard test 1-34 • Range: 10 mm cuvette: 0.2 - 5.0 mg/l CTAB 50 mm cuvette: 0.05 - 3.00 mg/l CTAB • Sufficient for: 40 determinations • Sea water suitability: no