Page:NIOSH Manual of Analytical Methods - 6008.pdf/2

 STIBINE: METHOD 6008, Issue 2, dated 15 August 1994 - Page 2 of 4 EQUIPMENT:

REAGENTS: 1. 2. 3. 4. 5. 6.

7.

Water, distilled or deionized. Hydrochloric acid (HCl), conc.* Antimony stock solution, 1000 µg/mL Sb(III). Ceric sulfate, Ce(SO 4)2, solid. Isopropyl ether. Rhodamine B stock solution, 0.2% in water. Dissolve 0.5 g Rhodamine B in 250 mL water. Prepare in duplicate. Working Rhodamine B solution, 0.01% in 0.5 M HCl. Dilute 25 mL Rhodamine B stock solution and 24 mL conc. HCl to 500 mL. Prepare fresh daily.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 7 cm long, 8-mm OD, 6mm ID, with plastic caps, containing two sections of HgCl 2-coated silica gel (front = 1.0 g; back = 0.5 g) separated and contained by silylated glass wool. Pressure drop across the tube at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Visible spectrophotometer capable of measuring absorbance at 552 nm, with two matched 1-cm silica absorbance cells with tight-fitting PTFE caps.* 4. Separatory funnels, 125-mL.* 5. Beakers, Griffin, 50-mL. 6. Volumetric flasks, 25-, 50-, 250-, and 500-mL. 7. Pipets, 4-, 15-, and 20-mL.* 8. Graduated cylinders, 10- and 25-mL.* 9. Centrifuge, with centrifuge tubes, 15-mL, with plastic caps.*

Clean all glassware with conc. HCl and rinse thoroughly with distilled or deionized water before use.

SPECIAL PRECAUTIONS: Perform all concentrated acid handling in a fume hood.

SAMPLING: 1. 2.

3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Remove sampler caps immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. NOTE: Use a cellulose ester membrane prefilter if particulate antimony compounds may be present. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 4 to 50 L. Cap the sampler and pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7. 8. 9. 10.

Place front and back sorbent sections of the sampler tube in separate 50-mL beakers. Discard the glass wool. Add 15.0 mL conc. HCl to each beaker. Mildly agitate (swirl) the beaker contents every 10 min for a total desorption time of 30 min. Pour the solution into a 25-mL volumetric flask. Add 4.0 mL conc. HCl to the sorbent in the beaker. Swirl and decant into the volumetric flask from step 7. Repeat step 8. Dilute to volume with conc. HCl and swirl to mix. NOTE: Perform steps 10 through 15 within a 15-min period. Pipet 15.0 mL of the sample extract into a separatory funnel. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94