Photometric determination of organic acids. • The determination of organic acids is carried out in two steps: 1. Esterification of organic acids with ethylene glycol. 2. Conversion of the esters to hydroxamic acids which subsequently react with iron(III) ions to form red coloured complexes. • Type: tube test 0-50. • Range: 30 - 3000 mg/l CH3COOH; 0.5 - 50.0 mmol/l CH3COOH. • Sufficient for: 20 determinations. • Sea water suitability: yes.