Page:NIOSH Manual of Analytical Methods - 2561.pdf/2

 AM INO E TH ANO L CO MP OU ND S: ME TH OD 2561, Issue 1, dated 1 5 Ma rch 2003 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5.

1.

Eluent: m etha nol* (chrom atog raph ic grade). Ana lytes, 99+% grade *. Helium, purified. Hydrogen, prepurified. Air, compressed, filtered.


 * See SPECIAL PRECAUTIONS.

2. 3. 4. 5. 6. 7. 8.

Sampler: glass tube, 7-cm long, 6-mm OD, flame-sealed ends, containing two sections of XAD-7 resin (front = 60 mg; back = 30 mg) separated by glass wool. Pressure drop across the tube at 0.1 L/min. airflow must be less th an 3.2 kP a. T ubes are com m ercially available (SKC, Inc. #226-94). Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. Refrigerant, bagged (“Blue Ice” or equivalent). Gas chromatograph, FID, integrator and colum n (page 25 61-1). Vials, glass, 2-mL, PTFE -lined crimp caps. Syringes, 10-µL to 500-µL. Volumetric flasks, 10-mL. Pipet, volumetric, 1-mL, with pipet bulb or repipet.

SPECIAL PRECAUTIONS: Methanol is toxic and flamm able. The analytes are eye irritants [2]. W ear 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 imm ediately before sampling. Attach sampler to personal sam pling pum p with flexible tubing. 3. Sa m ple at an acc urate ly known flow ra te betw een 0.02 and 0.1 L/m in for a total sam ple size of 10 to 24 L. 4. Cap the s am plers with plastic (not ru bbe r) caps a nd p ack sec urely for shipm ent w ith bag ged refrige rant.

SAMPLE PREPARATION: 5. Place the front and back sorbent sections of the sampler tube in separate vials. The initial glass wool plug may be discarded. 6. Ad d 1.0 m L of m eth anol eluent to each vial. Attac h crim p cap to each vial. 7. Allow to stand 60 min with occasional agitation.

CALIBRATION AND QUALITY CONTRO L: 8. Calibrate with at least six working standards over the range 4 to 4000 :g analyte per sample. a. Add known amounts of analyte to eluent in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samp les and blanks (steps 11 and 12). c. Prepare calibra tion gra ph (ratio of pea k area o f ana lyte vs. :g analyte). 9. Determine desorption efficiency (DE) at least once for each lot of XAD-7 used for sampling in the calibration range (step 8). Prepare three tubes at each of five concentrations plus three media blanks. a. Rem ove and disca rd back sorbent sec tion of a blank sam pler. b. Inject a known amount of analyte directly onto front sorbent section with a microliter syringe. c. Ca p the tube. Allow to stand overnight. d. Deso rb (steps 5 through 7 ) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. mg analyte recovered.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition