Page:NIOSH Manual of Analytical Methods - 2516.pdf/2

 DICHLOROFLUOROMETHANE: METHOD 2516, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1.

2. 3. 4. 5.

EQUIPMENT:

Eluent: carbon disulfide,* chromatographic quality, containing 0.4% v/v pentane as internal standard. Dichlorofluoromethane, 99%.* Nitrogen, purified. Hydrogen, prepurified. Air, filtered, compressed.

See SPECIAL PRECAUTIONS.

1. Sampler: two glass tubes connected in series with a short piece of plastic tubing; each tube 10 cm long, 8-mm OD, 6-mm ID, with plastic caps, containing 20/40 mesh activated (600 °C) coconut shell charcoal (front tube = 400 mg; back tube = 200 mg). A plug of silylated glass wool is placed at each end of each tube. Pressure drop across sampler less than 3.4 kPa (2.5 cm Hg) at 1 L/min airflow. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 0.05 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator and column (page 2516-1). 4. Vials, glass, serum, 10-mL, with PTFE-lined septa and crimp caps. 5. Syringe, 10-µL. 6. Syringes, gas-tight, 10-mL and 100-µL. 7. Syringe needles, 22-gauge.

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and an extreme fire and explosion hazard (flash point = -30 °C); work with it only in a hood. Dichlorofluoromethane may cause irregular heartbeat if inhaled [3].

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.05 L/min for a total sample size of 0.25 to 3 L. Separate the front and back tubes immediately after sampling. Cap the tubes. Pack securely for shipment.

SAMPLE PREPARATION: 5.

6.

7.

Place the front and back sorbent sections of the sampler in separate vials. Discard the glass wool plugs. Attach crimp cap to each vial. Insert a syringe needle vent through the septum to serve as a vent. Add 5.0 mL eluent to each vial with a syringe. Remove the syringe needle vent from the septum. NOTE: To avoid loss of analyte, do not add eluent to the charcoal before sealing the vial. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the range 0.05 to 35 mg (0.01 to 8.2 mL at 20 °C and 101 kPa) dichlorofluoromethane per sample. a. Add 5.0 mL eluent to each of a series of vials. Attach crimp cap to each vial. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94