Page:NIOSH Manual of Analytical Methods - 1010.pdf/2

 REAGENTS:

 Carbon disulfide, chromatographic quality.* Epichlorohydrin, reagent grade.* Nitrogen, purified. Hydrogen, prepurified. Air, filtered. Calibration stock solution, 9.45 mg/mL. Dissolve 80 µL epichlorohydrin in 10 mL CS2. 

* See SPECIAL PRECAUTIONS.

EQUIPMENT:  <li>Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm 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 airflow must be less than 3.4 kPa. Tubes are commercially available.</li> <li>Personal sampling pump, 0.01 to 0.2 L/min, with flexible tubing.</li> <li>Gas chromatograph, FID, integrator and column (page 1010-1).</li> <li>Vials, glass, 2-mL, PTFE-lined caps.</li> <li>Pipet, 1-mL, with pipet bulb.</li> <li>Syringes, 10- and 100-µL.</li> <li>Volumetric flasks, 1- and 10-mL.</li> <li>Metal file.</li> </ol>

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and extremely flammable (flash point = 30 °C); work with it only in a hood. Epichlorohydrin is a strong irritant and sensitizer and may cause kidney injury [4].

SAMPLING:

<ol> <li>Calibrate each personal sampling pump with a representative sampler in line.</li> <li>Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing.</li> <li>Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 2 to 30 L.</li> <li>Cap the samplers with plastic (not rubber) caps and pack securely for shipment.</li> </ol>

SAMPLE PREPARATION:

<li>Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs.</li> <li>Add 1.0 mL CS2 to each vial. Attach crimp cap to each vial.</li> <li>Allow to stand 30 min with occasional agitation.</li> </ol>

CALIBRATION AND QUALITY CONTROL:

<li>Calibrate daily with at least six working standards over the range 1 to 1200 µg epichlorohydrin per sample.</li> </ol> <ol style="list-style-type: lower-alpha;"> <li>Add known amounts of calibration stock solution to CS2 in 10-mL volumetric flasks and dilute to the mark.</li> <li>Analyze together with samples and blanks (steps 11 and 12).</li> <li>Prepare calibration graph (peak area vs. µg epichlorohydrin).</li> </ol> <li>Determine desorption efficiency (DE) at least once for each lot of charcoal used for sampling in </li></ol>