Page:NIOSH Manual of Analytical Methods - 1458.pdf/2

 METHYL ACETATE: METHOD 1458, Issue 2, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2. 3. 4. 5. 6.

EQUIPMENT:

Methyl acetate (reagent grade). Carbon disulfide (chrom. grade). Prepurified helium. Hydrogen, prepurified. Decane, reagent grade, or other suitable internal standard. Air, filtered, compressed.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4mm 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 must be less than 3.4 kPa. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Refrigerant, bagged ("Blue Ice," or equivalent). 4. Gas chromatograph equipped with FID, integrator and column (page 1458-1). 5. Vials, 2-mL, glass, PTFE-lined crimp caps. 6. Syringe, 10-µL, readable to 0.1 µL, and other convenient sizes. 7. Pipet, 1-mL, readable to 0.1 mL. 8. Volumetric flasks, 10-mL.

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and an acute fire and explosion hazard (F.P. = -30°C). Use only in a hood.

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 accurate flow rate between 0.01 and 0.2 L/min for a total sample size of 0.2 to 10 L. Cap the samplers with plastic caps and pack securely for shipment with bagged refrigerant.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Add 1.0 mL to CS 2 to each vial and attach a crimp cap to each vial. Allow to stand 30 minutes with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

9.

Calibrate daily with at least six working standards over the range 2 to 2000 µg analyte per sample. a. Add known amounts of analyte to CS 2 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 methyl acetate). Determine desorption efficiency (DE) at least once for each lot of charcoal used for sampling in the calibration range (step 8). Prepare three tubes at each of five concentrations plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94