Page:NIOSH Manual of Analytical Methods - 1024.pdf/2

 REAGENTS:

Methylene chloride, chromatographic quality with hydrocarbon (cyclohexene) preservative. 1,3-Butadiene, 99.5%, in cylinder equipped for gas withdrawal, with needle valve. Helium, purified. Hydrogen, purified. Air, purified. Nitrogen, purified. Water, distilled. </ol>

EQUIPMENT:

<ol><li>Sampler: Tandem charcoal tubes. Each tube is flame-sealed glass (8.5 cm long, 8-mm OD, 6-mm ID), has plastic caps for resealing, and contains activated coconut shell charcoal (such as SKC Lot 120) preceded by silylated glass wool and followed by a 3-mm urethane foam plug. The front tube holds 400 mg charcoal. The back tube holds 200 mg.</li> <li>Personal sampling pump, 0.01 to 0.5 L/min, with flexible connecting tubing./li> <li>Refrigerant, bagged (e.g., Blue Ice or dry ice), and insulated shipping container.</li> <li>Gas chromatograph, flame ionization detector, integrator, and column (see APPENDIX A).</li> <li>Ice, wet.</li> <li>Vials, 5-mL, 2-mL, 1-mL, and other convenient sizes, with PTFE-lined septum caps.</li> <li>Pipettes, TD, 4-, 2-, and 1-mL.</li> <li>Syringes, gas-tight, 250-, 100-, 25-, and 10-µL.</li> <li>Beaker, 150-mL.</li> <li>Gas drying tube with serum cap to fit stem and 2-cm piece of plastic tubing to fit over serum cap.</li> </ol>

SPECIAL PRECAUTIONS: 1,3-Butadiene is a potential carcinogen, teratogen, and reproductive hazard [2]. Methylene chloride is toxic, very volatile, and a suspect carcinogen [3]. Work should be performed in a well-ventilated fume hood.

SAMPLING:

<ol><li>Calibrate each personal sampling pump with a representative sampler in line.</li> <li>Immediately before sampling, break ends of sampler tubes. Connect smaller tube to personal sampling pump with flexible tubing and to larger tube with a short piece of plastic tubing.</li> <li>Sample at an accurately known flow rate of 0.01 to 0.5 L/min for a sample size of 5 to 25 L.</li> <li>Separate the tubes, cap, and pack securely for shipment. Chill below –4 °C during shipment and storage.</li> </ol>

SAMPLE PREPARATION:

<ol><li style="margin-bottom:0em;" value="5"> Add 4.0 mL methylene chloride to 5-mL vials and 2.0 mL to 2-mL vials. Loosely cap vials and thoroughly chill in ice.</li> <li>Place front sorbent sections in 5-mL vials and back sections in 2-mL vials. Discard glass wool and foam plugs. Immediately cap each vial.</li> <li>Remove from ice and allow to stand 30 min with occasional agitation.</li> <li>Transfer sample solution to appropriate vial and cap if using an autosampler. Thoroughly chill solution and vial before making transfer.</li> </ol>