Page:NIOSH Manual of Analytical Methods - 7902.pdf/2

 FLUORIDES, aerosol and gas by ISE: METHOD 7902, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4. 5. 6. 7. 8. 9.

10.

11.

12.

EQUIPMENT:

Sodium carbonate (Na 2CO 3). Glycerol. Potassium chloride (KCl). Sodium acetate (NaC 2H3O 2·3H 2O). Cyclohexylene diamine tetraacetic acid (CDTA). Hydrochloric acid, 1:1 (v/v). Sodium fluoride (NaF).* Deionized water. Fixative solution. Dissolve 25 g Na 2CO 3 in deionized water. Add 20 mL glycerol. Dilute to 1 L. Total ionic strength activity buffer (TISAB), pH 5.5. Dissolve 37 g KCl, 68 g sodium acetate and 36 g CDTA in H 2O. Adjust to pH 5.5 ± 0.2 with 1:1 HCl. Dilute to 1 L. Calibration stock solution, 100 µg/mL: Dissolve 0.2211 g NaF (dried at 105 °C for 2 h) in deionized water; dilute to 1 L. Sodium hydroxide, 20% (w/v). Dissolve 200 g NaOH in deionized water to make 1 L solution.



See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Fluorides are extremely corrosive to skin, eyes and mucous membranes [12]. Perform all fusions in fume hood.

SAMPLING: 1. 2. 3.

1. Sampler: cellulose ester membrane filter, 37mm, 0.8-µm pore size, with porous plastic backup pad (Nuclepore #220800, or equivalent), treated cellulose pad (Moisten with 0.8 mL fixative solution and dry at 105 °C for 30 to 45 minutes. Discard if charred.) in a 3-piece cassette with a 1/2" extension. Assembly of sampler: Place treated pad in rear (outlet) piece of cassette, insert 1/2-inch extension, place porous plastic pad and membrane filter in upper part of extension, and insert top piece (inlet) of cassette. Press tightly together and seal with shrink band or tape. NOTE: Leak test with hand vacuum pump. 2. Personal sampling pump, 1 to 2 L/min, with flexible connecting tubing. 3. Crucibles, nickel, zirconium, or Inconel, 20- or 30-mL. 4. Bunsen or Meaker burner. 5. Tripod. 6. Triangle, ceramic-covered. 7. Volumetric flasks, 50- and 100-mL, and 1-L. 8. Pipets, appropriate sizes for standards. 9. Beakers, plastic, 100-mL or 150-mL. 10. Magnetic stirrer. 11. PTFE-coated stirring bars. 12. Fluoride ion selective electrode (ISE), NaF combination or with calomel-type reference electrode. 13. pH/ion meter with millivolt readout and pH electrode. 14. Hand vacuum pump.

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 1 and 2 L/min for a total sample size of 12 to 800 L. Do not exceed 2 mg total dust loading on the filter. Pack securely for shipment.

SAMPLE PREPARATION: 4.

Cellulose ester membrane filter (particulate fluoride). NOTE: Water-soluble particulate fluorides may be extracted by the procedure for gaseous fluorides. Insoluble particles require fusion. a. Transfer the membrane filter to a crucible containing 5 mL 20% NaOH. b. Evaporate to dryness. c. Heat residue to fusion temperature, 1 to 2 min, cool and dissolve in ca. 5 mL deionized water. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94