Photometric determination of phosphate. • Photometric determination of the yellow phosphate-molybdate-vanadate complex after acidic hydrolysis and oxidation at 100-120 °C. • Ortho-phosphate ions react with molybdate/ vanadate to form a yellow phosphate-molybdate-vanadate complex. • Type: tube test 0-79 • Range: 10.0 - 50.0 mg/l P (PO4-P); 30 - 150 mg/l PO43- • Sufficient for: 19 determinations • Sea water suitability: yes