Photometric determination of chromate. • Photometric determination with diphenyl-carbazide. • In acidic medium, chromate ions react with diphenylcarbazide (lyophilised in the tube test) to form a red-violet colour complex. Chromium(III) ions are not determined unless they are converted to Cr(VI) by silver-catalysed oxidation with ammonium peroxodisulphate-/sulphuric acid. • Type: tube test 0-24 • Range: 0.1 - 4.0 mg/l CrO42-; 0.05 - 2.00 mg/l Cr(VI); when using semi-micro cuvettes 50 mm (Cat. No. 919 50): 0.01 – 1.00 mg/l CrO42-; 0.005 – 0.500 mg/l Cr(VI). • Sufficient for: 20 determinations • Sea water suitability: yes