ASTM D2318 Test Method for Quinoline-Insoluble (QI) Content of Tar and Pitch
12. Procedure
12.1 Make and record all weighings to the nearest 1 mg.
12.2 Select a sample mass that will yield between 75 mg and 150 mg of matter insoluble in quinoline (QI), unless this would require less than the minimum acceptable sample mass of 0.5 g, in which case 0.5 g shall be used.
12.3 Transfer 1 g +/- 0.1 g of dry CAFA to a clean, dry, filtering crucible. Weigh immediately, and record the mass of crucible plus CAFA.
12.4 Place the required amount of sample in a tared beaker and weigh. Calculate and record the mass of the sample. Transfer about half of the CAFA from the crucible to the beaker with sample. Distribute the remaining CAFA evenly over the bottom of the crucible.
12.5 Add 25 mL of quinoline to the beaker while stirring the mixture with a stirring rod or thermometer to break up lumps, then cover the beaker with a small watch glass. Place the beaker and a wash bottle containing quinoline on an electric hot plate or in a water bath maintained at 75 °C +/- 5 °C. (A suitable weight can be used to keep the beaker from being upset in the water bath.) Digest for at least 20 min. Occasionally stir the contents of the beaker to promote digestion. Check for completeness of digestion by inspecting the bottom of the beaker for undigested pitch.
12.6 Insert the filter tube with adapter in the filter flask, and place the previously prepared and tared crucible in the adapter. Carefully add sufficient quinoline to the crucible to wet the Celite thoroughly. Apply suction and form a mat of evenly distributed Celite. Maintain suction until filtration and subsequent washing with quinoline are completed.
12.7 Pour the hot quinoline-pitch mixture into the crucible, while the Celite in the crucible is still wet, without disturbing the mat. Stir the mixture in the beaker immediately before pouring successive portions into the crucible. Allow the contents to drain completely, but not to the extent that the insoluble material on the filter appears substantially dry.
12.8 Wash the beaker, thermometer, or stirring rod, and crucible with small portions (2 mL to 3 mL each) of quinoline at 75 °C +/- 5 °C from the wash bottle. Pass all the washes through the filter. Allow each wash to pass almost completely through the filter before the next is added. Use a suitable policeman to sweep the insoluble particles into the crucible. Repeat the quinoline washes until the filtrate is the same color as the quinoline used for washing. Twelve washings are usually enough.
12.9 After the final quinoline wash has passed through the filter, fill the crucible with toluene and wash with a total of 75 mL to 100 mL of toluene using suction. After all the toluene has passed through the filter, wash the contents of the crucible in the same manner with acetone. Maintain full suction for a minimum of 5 min after the acetone wash. Remove the crucible, and wipe the outside with a clean, soft cloth or tissue moistened with acetone.
12.9.1 During the quinoline and toluene washing do not allow the CAFA mat to get completely dry as the filtration rate may decrease considerably.
12.10 Place the filtering crucible in the drying oven at 105 °C to 110 °C and dry to constant weight (+/- 1 mg). When the hot crucible is removed from the drying oven it shall have no odor of quinoline. Transfer the crucible to the desiccator and cool for 25 min, then weigh and record the weight of the filtering crucible and its contents (see 12.1).
12.10.1 Insoluble matter on the filter, after washing with acetone, should have no odor of quinoline, which is evidence of insufficient washing. If odor of quinoline is detectable, repeat the entire determination.
12.11 If the mass of matter insoluble in quinoline is less than 75 mg or more than 150 mg, repeat the determination with an adjusted sample mass of not less than 0.5 g (see 12.2).
13. Calculation
13.1 Calculate the QI content as follows:
QI, mass% = [(A - B)/C] x 100
where:
A = total mass of the filtering crucible and CAFA added to the crucible, and matter insoluble in quinoline,
B = initial mass of the filtering crucible containing dried CAFA, and
C = mass of sample taken for the determination.
13.2 If the QI was determined on a wet tar sample (see 9.3.2), correct the QI value determined in 13.1 to a dry-tar basis as follows:
QI, mass % (dry basis) = QI, mass % (wet basis)/(100 - water content of tar, mass%) x 100
