Page:NIOSH Manual of Analytical Methods - 2552.pdf/2

 ME TH YL AC RYLA TE: M ETH OD 2552, Issue 1, dated 1 5 Ma rch 2003 - page 2 of 3 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5. 6.

1. Sampler: glass tube, 7 cm long x 6-mm ID, containing two sections of Anasorb CMS separated by a 3-mm section of polyurethane foam. Silanized glass wool plugs hold each section in place. Tubes are commercially available (SKC # 226 -121 or equivalent). 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible tubing. 3. Gas chromatograph, flame ionization detector (FID), integrator, and Rtx-35 fused silica capillary column. 4. Autosampler vials, glass, 12-mm crimp caps. 5. Syringes, 10-µL to 1-mL. 6. Volumetric flasks, 10-mL. 7. Pipets, various sizes.

Methyl acrylate, reagent grade (99 .9+).* Carbon disulfide, chromatographic grade*. Helium, purified. Hydrogen, purified. Air, prefiltered and purified. Calibration stock: Dilute 3 µL of Methyl acrylate in 10 m L solvent. Prepare remaining standards by serial dilution.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and flammable and should be handled in a well ventilated fume hood. Methyl acrylate reacts violently with strong oxidants resulting in an explosion and fire hazard. Methyl acrylate polymerizes easily under the effects of heat, light, and peroxides.

SAMPLING: 1. Calibrate each personal sampling pump with a representative sample tube in line. 2. Break open the ends of the sample tube immediately prior to sampling. Attach sample tube to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 1 to 5 L. 4. Cap both ends of the sample tubes with plastic caps and pack cold for shipment.

SAMPLE PREPARATION: 5. Place the initial glass wool plug and front sorbent section of the sample tube into autosampler vial. Place the back sorbent section of the sample tube in separate autosampler vial. Discard the polyurethane foam separator and the remaining glass wool plug. 6. Add 1.0 m L of carbon disulfide to each vial and cap securely. 7. Let each vial stand for 30 minutes with occasional agitation. 8. Analyze each sample by GC.

CALIBRATION AND QUALITY CONTROL: 9. Calibrate daily with at least six working calibration standards from below the LOD to 10 times the LOQ. If necessary, additional standards may be added to extend the calibration curve. a. Add known amounts of calibration stock solution to carbon disulfide solvent in 10-m L volumetric flasks and dilute to the mark. b. Analyze together with samples and blank s (steps 11 and 12). c. Prepare calibration graph (peak area vs. µg methyl acrylate). 10. Determine the desorption efficiency (DE) at least once for each lot of Anasorb CMS used for sampling in the calibration range (ste p 9). a. Prepare three tubes at each of five levels plus three media blanks. b. Inject a known amount of calibration stock solution directly onto the front sorbent section of each Anasorb CMS tube.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition