Page:NIOSH Manual of Analytical Methods - 1453.pdf/2

 VINYL ACETATE: METHOD 1453, Issue 3, dated 15 March 2013 - Page 2 of 4

REAGENTS:

EQUIPMENT:

1.	Vinyl acetate*, 99% purity, inhibited with 3 to 22 ppm hydroquinone 2.	Methanol*, distilled in glass 3.	Methylene chloride*, distilled in glass 4.	Desorption solvent, 95%/5% (v/v) methylene chloride/methanol 5.	Helium, purified 6.	Hydrogen, prepurified 7.	Air, filtered, compressed 8.	Calibration stock solution, 74.7 mg/mL. Add 400 µL vinyl acetate into a 5-mL volumetric flask and dilute to volume with methanol. * See SPECIAL PRECAUTIONS.

1.	Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends with plastic caps, containing two sections of carbon molecular sieve, Carboxen-564 (front = 160 mg, back = 80 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 25 mm/Hg. Tubes (carbon molecular sieve) are commercially available; Carboxen 564 or equivalent. 2.	Personal sampling pump, 0.1 to 0.2 L/min, with flexible connecting tubing 3.	Gas chromatograph with an FID detector, column (page 1453-1) and data collector 4.	Vials, 2-mL, with PTFE-lined caps 5.	Syringe, 10-µL and other sizes as needed 6.	Volumetric flasks, 2- and 5-mL

SPECIAL PRECAUTIONS: Methylene chloride is an irritant, can be absorbed through the skin, and is a potential occupational carcinogen. [7] Vinyl acetate can irritate the eyes, nose, and throat. Vinyl Acetate is flammable in air (percent by volume): lower, 2.6%; upper, 13.4%. [8] Vinyl acetate can become unstable if the polymerization inhibitor decreases to unsafe levels. [8] Methanol is flammable and a dangerous fire and explosion risk. It is moderately toxic by ingestion and inhalation. Wear appropriate protective clothing and work with these compounds 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 of 0.1 to 0.2 L/min for a total sample size of 1.5 to 24 L. NOTE: If high concentrations are expected, multiple samplers may need to be used to collect over an 8 hour period (collect two 4-hour samples for example) in order to not exceed the capacity of the sorbent tube. 4.	Cap the samplers. Pack securely for shipment. SAMPLE PREPARATION: 5.	Place the front sorbent section along with the glass wool plug in a separate vial from the back sorbent section of the sampler. Discard the foam plugs. 6.	Add 1.0 mL of 95:5% (v/v) methylene chloride/methanol to each vial. Cap each vial. 7.	Allow to stand 30 min with occasional agitation.

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition