TEST SUMMARY
This test method is applicable for the determination of phosphorus in the range from 0.2 to 40 mg/L. Organic matter in the sample is decomposed by ignition in the presence of zinc oxide. The residue is dissolved in sulfuric acid and reacted with ammonium molybdate and hydrazine sulfate. The absorbance of molybdenum blue complex is measured at 820 nm in a 5-mm cell in a spectrophotometer, and is proportional to the phosphorus concentration in the sample.
TEST PRECISION
Bias of this test method has not been determined.