Page:NIOSH Manual of Analytical Methods - 2000.pdf/2

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METHANOL: METHOD 2000, Issue 3, dated 15 January 1998 - Page 2 of 4 EQUIPMENT:

REAGENTS:

1. Sampler: silica gel tube, 7 cm long, 4-mm ID, Methanol, chromatographic grade. * containing two sections of 20/40 mesh silica gel Water, distilled and prepurified. (front = 100 mg, back = 50 mg) separated by a Isopropanol (IPA), chromatographic grade.* 2-mm urethane foam plug. A silylated glass Helium, purified. wool plug precedes the front section. A 4-mm Hydrogen, prepurified. foam plug follows the back section. Samplers Air, filtered. are commercially available. Desorbing solution, 5% isopropanol in 95% NOTE: At high relative humidity or high distilled water. methanol concentrations, use a larger 8. Calibration stock solution, 2µg/µL. Add 25.3µL tube: 15 cm long, 8-mm ID, with three Methanol to 10 mL of desorbing solution. sections of silica gel (700 mg, 150 mg, 150 mg). 2. Personal sampling pump, 0.02 to 0.2 L/min,

See SPECIAL PRECAUTIONS

with flexible connecting tubing. 3. Gas chromatograph, flame ionization detection, integrator, and Rtx-35 capillary column, or equivalent (page 2000-1). 4. Utrasonic bath. 5 Vials, autosampler, with PTFE-lined caps. 6. Microliter syringes, 10-µL and other sizes as needed, readable to 0.1 µL. 7. Flasks, volumetric, various sizes. 8. Pipets, various sizes. 1. 2. 3. 4. 5. 6. 7.

SPECIAL PRECAUTIONS: Methanol is flammable and a dangerous fire and explosion risk. It is moderately toxic by ingestion and inhalation. Isopropanol is flammable and a fire risk. Wear appropriate protective clothing and work with these compounds in a well ventilated hood.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break ends of sampler immediately before sampling.Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.02 and 0.2 L/min for a total sample size of 1 to 5 L. Cap the samplers with plastic caps and pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place front (include glass wool plug) and back sorbent sections of the sampler tube in separate vials. Discard foam plugs. Add 1 mL of water/IPA (95/5) to each vial and attach crimp caps. Place vials in an ultrasonic bath for 30 to 60 min to aid desorption.

CALIBRATION AND QUALITY CONTROL: 8.

9.

Calibrate daily with at leastsix working standards over the range of interest. Three standards (in duplicate) should cover the range from LOD to LOQ. a. Add known amounts of calibration stock solution to water/isopropanol (95/5) 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 or height vs. µg methanol). Determine desorption efficiency (DE) at least once for each lot of silica gel tubes used for sampling NIOSH Manual of Analytical Methods (NMAM), Fourth Edition