1 Subject Content and Application Scope
This standard specifies the determination method for phosphorus content of gasoline.
This standard is applicable to determine the phosphorus content in gasoline, which exists in the form of pentavalent phosphate or salt or coexistence of the both. The measurement range is 0.2~40mg/L.
2 Summary of Method
Under the existence of ZnO, the organic substance of the specimen decomposes through calcination, the calcinated residue dissolves in sulfuric acid and produces molybdenum blue complex through reaction with ammonium molybdate and hydrazine sulfate. Take distilled water as reference solution and measure its absorbance at 820nm of wavelength in the cuvette of 5cm optical path; calculate the phosphorus content of the specimen in accordance with the proportion of the absorbance of the molybdenum blue complex and the P concentration.
3 Apparatus and Materials
3.1 Apparatus
a. Spectrophotometer: the wavelength range is 420~9,130nm attached with cuvettes of 5cm and 1cm;
b. Pipette: 10mL, the division value is 0.1mL; 2mL, the division value is 0.02mL;
c. Constant temperature bath: equipped with a support, which are capable of immersing the 100mL-volumetric flask to the scribe line and maintaining a constant temperature at (85±2)℃;
Note: If the temperature of hot bath is below 83℃, its coloration is incomplete.
d. Cooling bath: equipped with a support which are capable of immersing the 100mL-volumetric flask to the scribed line;
e. Burning dish: Gooch porcelain evaporating dish with enameled interior and exterior and a volume of 100mL;
f. Thermometer: 0~100℃, the division value is 1℃;
g. Volumetric flask: 100, 1000mL;
h. High temperature furnace;
i. Injector: 10mL, equipped with a 5cm length pinhead.
3.2 Materials
Filter paper: medium speed quantitative filter paper, the diameter is 9cm.
