ASTM D3231 Standard Test Method for Phosphorus in Gasoline
3. Summary of Test Method
3.1 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 the Molybdenum Blue complex is proportional to the phosphorus concentration in the sample and is read at approximately 820 nm in a 5-cm cell.
4. Significance and Use
4.1 Phosphorus in gasoline will damage catalytic convertors used in automotive emission control systems, and its level therefore is kept low.
