Principle Total phosphoric compounds in water sample is changed to phosphate (PO4 -) form by oxidation. After treatment with ammonium molybdate • ascorbic acid solution, blue color is created. This color is measured at 880 nm. In this application note, the quantitative analysis of total phosphorus (T-P) was performed by as-corbic acid method. Data are rapidly acquired using LAMBDA™ 465 UV-Vis Spectrophotometer and processed using UV Lab™ Software.