Orthophosphate Calculator
Definition: Orthophosphate reacts with ammonium molybdate and potassium antimonyl tartrate in acidic solution. Reduction with ascorbic acid produces a blue-colored complex whose absorbance is used to determine phosphorus concentration.
Orthophosphate-P (mg/L) =
[(A − b) / m] × DF
A = sample absorbance
b = calibration curve intercept
m = calibration curve slope
DF = dilution factor
Method basis: Standard Methods for the Examination of Water and Wastewater, Method 4500-P E — Ascorbic Acid Method. Results from the calibration curve are reported as phosphorus (P).