Page:NIOSH Manual of Analytical Methods - 1552.pdf/2

 TERPENES: METHOD 1552, Issue 1, dated 15 May 1996 - page 2 of 4 REAGENTS:

EQUIPMENT:

1. Carbon disulfide (CS2), chromatographic grade.* 2. Limonene, reagent grade.* 3. -Pinene, reagent grade.* 4. -Pinene, reagent grade.* 5. 3-Carene, reagent grade.* 6. Helium, prepurified. 7. Hydrogen, purified. 8. Air, filtered, dry.

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends, 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. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible tubing. 3. Gas chromatograph with flame ionization detector, integrator, and column (p. 1552-1). 4. Vials, 2-mL, glass, PTFE-lined crimp caps. 5. Syringes, 10- and 25-µL, readable to 0.1 µL. 6. Pipets, various sizes for standard preparation. 7. Volumetric flasks, 10-mL.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Carbon disulfide is toxic, flammable, and explosive (flash point = -30 C). Terpenes are flammable and are considered irritants. Perform all work in a well ventilated hood.

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 2 to 30 L. 4. Cap the samplers with plastic caps and pack securely for shipment. NOTE: Store samples at 5 C. Analyze as soon as possible to reduce risk of analyte rearrangement (see EVALUATION OF METHOD). SAMPLE PREPARATION: 5. Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. 6. Add 1.0 mL CS2 to each vial. Attach crimp cap to each vial. 7. Allow to stand 30 min with occasional agitation. CALIBRATION AND QUALITY CONTROL: 8. Calibrate daily with at least six working standards over the range from 0.2 to 1000 µg per sample. a. Add known amounts of analyte to CS2 in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare a calibration graph for each analyte (peak area or peak height vs. µg analyte). 9. Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount of analyte directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze together with working standards and blanks (steps 11 and 12). e. Prepare graph of DE vs. µg analyte recovered for each analyte. 10. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration and DE graphs are in control.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition