National Institute for Occupational Safety and Health

“ Isopropyl ether*, reagent grade. 3. Helium, prepurified and filtered. 4. Hydrogen, prepurified and filtered. 5. Air, prepurified and filtered.
1. Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends, containing two sections of activated coconut shell charcoal (front = 100 m g, back = 50 m g) separated by a 2-mm urethane foam plug. A silanized glass wool plug precedes the front section, and a 3-mm urethane foam plug follows the back section. Tubes are comm ercially available. 2. Personal sampling pumps (0.01 to 0.05 L/min) with flexible tubing. 3. ”

“ Add known amounts of isopropyl ether to eluent in 10-mL volumetric flasks and dilute to the mark. Prepare additional standards by serial dilution in 10-mL volumetric flasks. b. Analyze with samp les and blanks (steps 11 and 12) . c. Prepare a calibration graph (pe ak area of analyte vs. mg of ana lyte per sam ple) . 9. Determine the desorption efficiency (DE) at least once for each lot of charcoal used for sampling in the calibra tion ran ge (s tep 8) . ”

“ Inject a known amount of stock solution (1 to 20 μL) directly onto the front sorbent se ction with a microliter syringe. d. Allow the tubes to air equilibrate for several minutes, then cap the tubes and allow to stand overnight. e. Deso rb (steps 5 through 7 ) and analyze with standards and blank s (steps 11a nd 12) . f. Prepare a graph of DE vs. μg analyte recovered. g. Analyze a m inim um of thre e qu ality contro l blind sp ikes and three a nalyst spikes to insure that the calibra tion gra ph and D E graph are in control. h. ”