Photometric determination of sulphide. • Photometric determination as methylene blue. • N,N-Dimethyl-1,4-phenylene diamine reacts with hydrogen sulphide to form a compound which changes to leucomethylene blue. This compound is oxidised to methylene blue using iron(III) ions. • Type: standard test 1-88 • Range: 10 mm cuvette: 0.1 - 3.0 mg/l S2- 50 mm cuvette: 0.01 - 0.60 mg/l S2- • Sufficient for: 250 determinations • Sea water suitability: yes