Page:NIOSH Manual of Analytical Methods - 1606.pdf/2

 ACETONITRILE: METHOD 1606, Issue 3, dated 15 January 1998 - Page 2 of 3 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5. 6.

1. Sampler: glass tube, 10 cm, 6-mm ID, flamesealed ends with plastic caps, containing two sections of 20/40 mesh activated coconut shell charcoal (front = 400 mg, back = 200 mg), separated by a 3-mm section of polyurethane foam. A silanized glass wool plug precedes the front section and a 3-mm polyurethane plug follows the back section. Tubes are commercially available (SKC # 226-09, Supelco ORBO-32, or equivalent). 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible tubing. 3. Gas chromatograph, flame ionization detector (FID), integrator, and Stabilwax® fused silica capillary column, or equivalent (page 1606-1). 4. Vials, glass, 4-mL, PTFE-lined screw caps. 5. Syringes, 10-µL to 1-mL. 6. Volumetric flasks, 10-mL. 7. Pipets, various sizes. 8. Refrigerant packs.

Acetonitrile (ACN), reagent grade (99.9+%)*. Methylene chloride, HPLC grade*. Methanol, HPLC grade*. Helium, purified. Hydrogen, purified. Air, prefiltered and purified.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Acetonitrile is toxic and flammable. Methylene chloride is a potential carcinogen. Methanol is moderately toxic and flammable. Perform all work in a chemical hood and wear appropriate protective equipment. SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sample tube in line. Break open the ends of the sample tube immediately prior to sampling. Attach sample tube to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 1 to 25 L. Cap both ends of the sample tubes with plastic caps and pack securely for shipment. Ship with refrigerant packs to keep samples cold.

SAMPLE PREPARATION: 5.

6. 7. 8.

Place the initial glass wool plug and front sorbent section of the sample tube in a 4-mL glass screw cap vial. Place the back sorbent section of the sample tube in separate 4-mL vial. Discard the polyurethane foam plugs. Add 2.0 mL of methylene chloride/methanol (85:15) to each 4-mL vial and cap securely. Place each vial in an ultrasonic bath for 45 minutes. Transfer 1.0-mL aliquots of each sample to autosampler vials and analyze (steps 11 and 12).

CALIBRATION AND QUALITY CONTROL: 9.

Calibrate daily with at least six working calibration standards over the range of interest. a. Add known amounts of calibration stock solution (prepare in concentration range of samples; 1 µL ACN = 78.3 µg) to methylene chloride/methanol (85:15) in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. µg acetonitrile). 10. Determine the desorption efficiency (DE) atleast once for each batch of charcoal used for sampling NIOSH Manual of Analytical Methods (NMAM), Fourth Edition