Astm D3231 Phosphorus In Gasolines

ASTM D3231
Phosphorus in Gasoline

1. Before starting the preparation : Open UV (Library, D3231), setting the bath at 85 °C and setting the oven at 700 °C.

2. Digestion of samples:

2.1. Usecrucibles of porcelain, sample and blank. Transfer 2 g of zinc oxide in each crucibles. Make a deep depression in the center of the zinc oxide.
2.2. Pipette 2 mL of gasoline. Cover with zinc oxide(0.2g), burn gasoline.
2.3. Allow the crucible to cool and repeat 4 times step 2.2 (10 mL total gasoline).
2.4. Place the crucibles in the furnace at 700 °C for 10 minutes.
2.5. Remove and cool toroom temperature. Tap the sides of the crucibles to loosen the zinc oxide and return to the oven for 5 minutes. Cool to room temperature.
2.6. Pipette in all crucibles, 25 ml of H2SO4 (1 +10). Coverwith a watch glass and place on plate heat until clear solution.
2.7. Transfer to a 100 mL volumetric flask using filter paper, rinse the watch glass several times (not to exceed 25 mL)

3. Prepare200 mL of Molybdate-Hydrazine. This reagent is unstable and must be used within about 4 hours.

3.1. Pipette 50 ml of ammonium molybdate in 200 mL volumetric flask containing about 100 ml of water,add 20 ml of hydrazine sulfate and complete a 200 ml with water.

4. Preparation of calibration curve: (100 mL volumetric flask)

| |Blank|0,2 ug P/mL |Sample |
|Standard Solution 10 ug P/mL |--- |2 mL |--- |
|H2SO4 (1+10)|--- |10 mL |--- |
|Molybdate-Hydrazine Reagent |50 mL |50 mL|50 mL |

4.1. Mix immediately and dilute with distilled water.
4.2. Place 30 minutes to the bath at 85 °C. Cool in ice water bath.
4.3. Remove the volumetric flask of ice...