Page:NIOSH Manual of Analytical Methods - 5036.pdf/2

 TRIMELLITIC ANHYDRIDE: METHOD 5036, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4. 5. 6.

7. 8.

9. 10. 11.

EQUIPMENT:

Methanol; ACS reagent grade. Pentane, ACS reagent grade.* Diethyl ether, ACS reagent grade.* Boron trifluoride/methanol, 14° (w/v) mixture* (commercially available from GC suppliers). Pyridine, ACS reagent grade. Pyridine mixture,* prepare a 7:3 pyridine/pentane mixture in a screw-cap tube. Trimellitic anhydride. Calibration stock solution, 1.92 µg/µL. Dissolve 0.4803 g of trimellitic anhydride in methanol and dilute to 250 mL. Hydrogen, prepurified. Air, compressed, filtered. Helium, purified.



See SPECIAL PRECAUTIONS.

1. Sampler: 37-mm, PVC-copolymer filter (0.8µm pore size) supported by a cellulose backup pad in a three-piece plastic filter holder. 2. Personal sampling pump, 1.5 to 2 L/min with flexible polyethylene or PTFE tubing. 3. Gas Chromatograph, FID, integrator and column. 4. Test tubes, glass, (13 x 100-mm) with teflonlined screw caps. 5. Syringe, 10-µL. 6. Pipettes, 10-µL, 25-µL, and 0.25 - 5-mL. 7. Volumetric flask, 250-mL. 8. Beakers, 50-mL and 250-mL. 9. Hotplate, variable heat settings. 10. Watch Glasses, for 50-mL beakers. 11. Ultrasonic bath. 12. Septa, high temperature (350 °C), GC injection. 13. Analytical balance, to ± 0.01 mg. 14. Tweezers 15. Applicator stick. 16. Weighing paper.

SPECIAL PRECAUTIONS: Diethyl ether and pentane are extremely flammable. Boron SAMPLING: trifluoride and pyridine are toxic. Work with these substances only in a hood. 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Connect the filter holder to the pump with a piece of flexible tubing. 3. Sample at an accurately known flow rate between 1.5 and 2 L/min for a total sample size of 400 L or greater. Collect a larger sample if a qualitative analysis is to be performed. 4. Replace filter plugs, and pack securely for shipment.

SAMPLE PREPARATION: 5.

Extraction: a. Place a field sample or spiked filter sample in a 50-mL beaker. b. Add 3 mL of methanol. c. Cover the beaker with a watch glass and place on a hot plate (65 °C) for one minute. d. Remove the beaker with the watch glass still in place and place in the ultrasonic bath for one minute. e. Rinse the bottom of the watch glass with 1 mL of methanol, collect the rinse in the beaker. f. Lift the filter with tweezers above the methanol level and rinse both sides of the filter slowly with two 3-mL aliquots of methanol, collecting the rinse in the beaker. g. Roll and squeeze the filter with tweezers against the inside wall of the beaker to remove methanol retained by the filter. h. Discard the filter. i. Place the beaker on the hot plate (55 °C) and evaporate the methanol to volume less than 5 mL. j. Transfer the methanol extract to a test tube.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94