Page:NIOSH Manual of Analytical Methods - 5523.pdf/2

 GLYCOLS: METHOD 5523, Issue 1, dated 15 May 1996 - Page 2 of 5 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5. 6. 7. 8.

1. Sampler: XAD-7 OVS tube, 13-mm OD, containing two sections of XAD-7 (200 mg front/100 mg back section) separated by polyurethane foam plug. A glass fiber filter plug precedes the front section and a polyurethane foam plug follows the back section. Tubes are commercially available (SKC, Inc., #226-57). 2. Personal sampling pump, 0.5 to 2 mL/min, with flexible connecting tubing. 3. Gas chromatograph, flame ionization detector, integrator, and column (page 5523-1). 4. Ultrasonic bath. 5. Vials, autosampler, with PTFE-lined caps. 6. Vials, 4 mL, with screw caps. 7. Syringes, 10-µL and other sizes as needed, readable to 0.1 µL. 8. Flasks, volumetric, various sizes. 9. Pipets, various sizes.

Ethylene glycol, reagent grade.* Propylene glycol, reagent grade.* 1,3-Butylene glycol, reagent grade.* Diethylene glycol, reagent grade.* Triethylene glycol, reagent grade.* Tetraethylene glycol, reagent grade.* Methanol, chromatographic grade.* Calibration stock solution, 10 mg/mL: Weigh aliquots of each glycol and dissolve in methanol. 9. Helium, purified. 10. Hydrogen, prepurified. 11. Air, filtered.
 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Inhalation of glycol mists causes respiratory irritation, shortness of breath, and coughing. Methanol is flammable and a dangerous fire risk. Work with these compounds in a wellventilated hood. SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Remove front and rear caps from the tube immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 0.5 and 2 L/min for a total sample size of 5 to 60 L. 4. Cap the samplers and pack securely in dry ice for shipment.

SAMPLE PREPARATION: 5. Place front sorbent section and glass fiber filter in a 4-mL screw cap vial. Place backup sorbent section in a separate vial. Discard foam plugs. 6. Add 2 mL of methanol to each vial and cap. 7. Place vials in an ultrasonic bath for 30 min to aid desorption.

CALIBRATION AND QUALITY CONTROL: 8. Calibrate daily with at least six working standards over the range of interest. Three standards (in duplicate) should cover the range from LOD to LOQ. a. Add known amounts of calibration stock solution to methanol in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area or height vs. µg glycol). 9. Determine desorption efficiency(DE) at least once for each lot of OVS tubes used for sampling in the calibration range (step 8). a. Prepare three samplers at each of six levels plus three media blanks. b. Inject a known amount of calibration stock solution directly onto the filter of OVS tubes. Draw air NIOSH Manual of Analytical Methods (NMAM), Fourth Edition