Page:NIOSH Manual of Analytical Methods - 1618.pdf/2

 ISOP RO PYL ET HER : MET HO D 161 8, Issue 2, dated 15 M arch 200 3 - Page 2 o f 4 REAGENTS:

EQUIPMENT:

1. Eluent: Carbon disulfide* (CS2), chrom ato graphic quality. 2. 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. Gas chromatograph, FID, integrator, and Rtx®1 or equivalent capillary column (see page 16 18-1). 4. Glass a utos am pler vials (2-m L) with PTFE-lined caps. 5. Pipettes (1-mL) and pipette bulb. 6. Microliter syringes, 10-µL and convenient sizes for making dilutions. 7. Volum etric flasks (10-m L).


 * See SPECIAL PRECAUTIONS

SPE CIAL PRECAUTIONS: Carbon disulfide is toxic and highly flamm able (flash point = -30 °C); isopropyl ether is flam m able and tends to fo rm exp losive pero xides [4]. Prepare samples and standards in a well-ventilated hood. SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sam pler im m ediately befo re sa m pling. Attach the sam pler to a personal sampling pump with flexible tubing. 3. Sa m ple at an accurately known flow rate betw een 0.01 and 0.05 L/m in for a total sam ple size of 0.1 to 3 L. 4. Ca p the sam plers and pac k secu rely for shipm ent.

SAMPLE PREPARATION: 5. Place the front and back sorbent sections of the sampler tube in sep arate vials. Include the glass wool plug in the vial with the front sorbent section. Discard the foam plugs. 6. Ad d 1.0 m L eluent to each vial. Attach crim p cap to each vial im m ediate ly. 7. Allow to stand at least 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTRO L: 8. Ca librate daily with at leas t six wo rking standa rds from below the LOD to 10 times the LO Q. Additional sta ndards m ay be added to exte nd the calibra tion curve if ne cessary. a. 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).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition