Page:NIOSH Manual of Analytical Methods - 6006.pdf/2

 DIBORANE: METHOD 6006, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3.

4.

EQUIPMENT:

Diborane, 1% (v/v), certified gas mixture.* Hydrogen peroxide (H 2O 2), 3% w/v in deionized water. Calibration stock solution, 1000 µg B/mL, commercially available or dissolve 0.572 g boric acid (H 3BO 3) in deionized water to make 100 mL solution. Store in a polyethylene bottle. Argon, for DC plasma excitation.

See SPECIAL PRECAUTIONS.

1. Sampler: a. PTFE membrane filter, 13-mm diameter, 1-µm pore size (e.g., Millipore FALP), in a plastic cassette (Millipore SX00013 or equivalent). b. Glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends with plastic caps, containing two sections (100 mg and 50 mg) of oxidizer-impregnated charcoal; separated and retained by silylated glass wool plugs. 2. Personal sampling pump, 0.5 to 1 L/min, with flexible connecting tubing. 3. Plasma emission spectrometer with a DC plasmaexcitation source. 4. Pipets, plastic, 10-mL, and 5- to 50-µL. 5. Volumetric flasks, plastic, 10-mL. 6. Bottles, screw-top, plastic, 60-mL. 7. Syringe, plastic, 10-mL, fitted with 0.5-µm PTFE filter. 8. Vials, plastic, 7-mL, screw-on septum caps. 9. Ultrasonic bath. 10. Gas-tight syringes, 0.5- and 5-mL, graduated.

SPECIAL PRECAUTIONS: Diborane is very toxic and flammable, having an Immediately Dangerous to Life or Health (IDLH) level of 40 ppm. It is a strong irritant with a repulsive, sweet odor [3]. SAMPLING: 1. 2.

3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the charcoal tubes immediately before sampling. Attach the filter cassette in front of the charcoal tube with a short piece of tubing. Attach the outlet of the charcoal tube to the personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.5 and 1 L/min for a total sample size of 60 to 260 L. Separate the filter and the charcoal tube. Cap the charcoal tube. Pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Pipet 10.0 mL 3% H 2O 2 into a series of plastic bottles. Quickly add the front and back charcoal sections to separate bottles and screw on the caps. Discard the glass wool plugs. Allow to stand 30 min and then place in an ultrasonic bath for 20 min. Draw the sample through a 0.5-µm PTFE membrane filter with a syringe.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution to 3% H 2O 2 in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain boron concentrations in the range 0.1 to 4 µg B/mL. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94