Page:NIOSH Manual of Analytical Methods - 7905.pdf/2

 PHOSPHORUS: METHOD 7905, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4.

5. 6. 7. 8.

EQUIPMENT:

Phosphorus (white), purified, stored under distilled water.* Xylene (mixed), reagent grade. Acetone, purified. Calibration stock solution, 0.20 mg/mL. Prepare under nitrogen or other inert gas. Dissolve a known mass (ca. 2 mg) of acetonewashed, dried white phosphorus in 10 mL xylene. Stir until dissolved. Prepare in duplicate. Helium, prepurified. Hydrogen, prepurified. Air, compressed, filtered. Nitrogen, purified.

See SPECIAL PRECAUTIONS.

1. Sampler: borosilicate glass tube, 7-cm long, 8mm OD, 6-mm ID, flame-sealed ends with plastic caps, containing two sections of 35/60 mesh Tenax GC (front = 100 mg; back = 50 mg) separated and retained by 2-mm silylated glass wool plugs. Pressure drop across the sampler at 0.2 L/min airflow must be less than 3.3 kPa (25 mm Hg). NOTE: If the air sample is expected to contain particulate elemental phosphorus, precede the Tenax tube with a 37-mm diameter, cellulose ester membrane filter. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, flame photometric detector (phosphorus mode), integrator and column (page 7905-1). 4. Vials, 20-mL, PTFE-lined septum caps. 5. Syringes, 5-, 10- and 25-µL, for making standards and GC injections. 6. Volumetric flasks, 10-mL. 7. Pipet, TD, 1-mL with pipet bulb. 8. Balance, analytical, readable to 0.01 mg.

SPECIAL PRECAUTIONS: White phosphorus may be fatal if ingested, even in small quantities [5]. Phosphorus vapor is toxic; work in a contained atmosphere with adequate care. SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 5 to 100 L. Cap the samplers and pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool plugs. Pipet 1.0 mL xylene into each vial. Cap each vial. NOTE: Use 5.0 mL xylene for filters, if applicable. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution, or a serial dilution thereof, to xylene in 10-mL volumetric flasks and dilute to the mark to produce phosphorus concentrations in the NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94