SULFUR DIOXIDE: METHOD 6004, Issue 2, dated 15 August 1994 - Page 2 of 4 EQUIPMENT:
REAGENTS: 1. 2.
3.
4.
Water, deionized, filtered, specific conductance ≤10 µS/cm. Fixative solution. Dissolve 25 g Na 2CO 3 in deionized water. Add 20 mL glycerol and dilute with deionized water to 1 L. Eluent: 1.75 m M NaHCO 3/2.0 mM Na 2CO 3. Dissolve 0.588 g NaHCO 3 and 0.848 g Na 2CO 3 in 4 L filtered deionized water. Calibration stock solutions, 1 mg/mL (as the anion). Prepare in duplicate. a. Sulfite: dissolve 0.1575 g Na 2SO 3 in water. Add 2 mL glycerol. Dilute to 100 mL. Prepare fresh daily. b. Sulfate: dissolve 0.1479 g Na 2SO 4 in deionized water. Dilute to 100 mL. Stable several weeks.
See SPECIAL PRECAUTIONS.
1. Sampler: two 37-mm diameter cassette filter holders (connected in series by a M-M Luer adapter, e.g., Millipore XX1102503, or a short piece of plastic tubing) containing: a. (Front cassette) cellulose ester membrane filter, 0.8-µm pore size, supported by a backup pad. b. (Back cassette) cellulose filter (Whatman 40 or equivalent) which has been saturated with fixative solution and dried 20 to 30 min at 100 °C, supported by a porous plastic support pad. 2. Personal sampling pump, 0.5 to 1.5 L/min, with flexible connecting tubing. 3. Vials, glass, 20-mL, screw-cap, such as scintillation vials.** 4. Ion chromatograph, HPIC-AS4A anion separator and HPIC-AG4A guard, anion micromembrane suppressor, conductivity detector, and strip chart recorder. (Optional: integrator.) 5. Syringes, 10-mL, polyethylene, with luer tip.** 6. Filters, in-line, luer-tip holder with membrane filter, 13- or 25-mm, 0.45-µm pore size. 7. Micropipets, 50- to 1000-µL, with disposable tips.** 8. Volumetric flasks, 50- and 100-mL.** 9. Pipet, 10-mL.** 10. Polyethylene bottles, 250-mL.**
Clean by rinsing thoroughly with deionized water.
SPECIAL PRECAUTIONS: None.
SAMPLING: 1. 2. 3. 4.
Calibrate each personal sampling pump with a representative sampler in line. Remove end caps of sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.5 and 1.5 L/min for a total sample size of 40 to 200 L. Do not exceed a total particulate loading of 2 mg on the front filter. Seal the sampler and pack securely for shipment. NOTE: If determination of sulfuric acid is required, transfer the front (membrane) filter to a clean vial within 4 h to avoid low recovery of sulfate. Handle the filter with tweezers to avoid contamination.
SAMPLE PREPARATION: 5. Put the two filters from the sampler into separate, clean vials. Discard the backup pads. Add 10.0 mL eluent to each vial and let stand, with occasional vigorous shaking, for 30 min. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
