Page:NIOSH Manual of Analytical Methods - 1613.pdf/2

 PYRIDINE: METHOD 1613, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4.

5. 6. 7.

EQUIPMENT:

M e t h y l e n e chloride (CH 2Cl 2) , chromatographic quality. Pyridine, reagent grade.* Hexane, chromatographic quality. DE stock solution, 300 mg/mL. Weigh 3 g pyridine (ca. 3.1 mL) into a 10-mL volumetric flask. Dilute to volume with hexane. Prepare in duplicate. Nitrogen, purified. Hydrogen, prepurified. Air, filtered, compressed.

1.

2. 3. 4. 5. 6. 7. 8.
 * See SPECIAL PRECAUTIONS.

Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends, with plastic caps, containing two sections of activated (600 °C) coconut shell charcoal (front = 100 mg; back = 50 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and a 3-mm urethane foam plug follows the back section. Pressure drop across the tube at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. Personal sampling pump, 0.01 to 1 L/min, with flexible connecting tubing. Gas chromatograph, flame ionization detector, integrator and column (page 1613-1). Vials, 2-mL, PTFE-lined crimp caps. Syringes, 10-µL, readable to 0.1 µL. Volumetric flasks, 10-mL. Pipet, TD, 1-mL. Balance, analytical.

SPECIAL PRECAUTIONS: Pyridine can cause liver and kidney damage, and CNS depression if it is inhaled or contacts the eyes or skin [4,5]. Methylene chloride is a suspect carcinogen [6].

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 1 L/min for a total sample size of 18 to 150 L. Cap the samplers. Pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Pipet 1.0 mL CH 2Cl2 into each vial. Cap each vial. NOTE: A suitable internal standard, such as toluene, may be added at this step [2]. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards. a. Add known amounts of pyridine to CH 2Cl2 in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain pyridine concentrations in the range 0.02 to 4.5 mg/mL. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. mg pyridine). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94