Page:NIOSH Manual of Analytical Methods - 1008.pdf/2

 ETHYLENE DIBROMIDE: METHOD 1008, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4.

5. 6. 7.

EQUIPMENT:

Benzene, pesticide quality.* Methanol, pesticide quality.* Ethylene dibromide, high purity (density=2.169 g/mL @ 25 °C).* An appropriate internal standard such as 1,1,2,2-tetrachloroethane (density = 1.587 g/mL @ 25 °C) or 1,2-dibromopropane (density = 1.923 g/mL @ 25 °C). 99:1 benzene:methanol (v/v). Eluent*: 99:1 benzene:methanol (v/v) containing 0.1 µg internal standard/mL. Calibration stock solution, 10 ng/µL. Dissolve 50 mg ethylene dibromide in benzene to make 25 mL solution. Dilute 50 µL of this solution to 10 mL with benzene. Stable 3 weeks if refrigerated.

See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4mm ID, flame-sealed ends with plastic caps, containing two sections of 20/40 mesh activated (600 °C) coconut shell charcoal (front = 100 mg; back = 50 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and a 3-mm urethane foam plug follows the back section. 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, 0.02 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, 63Ni electron-capture detector, integrator and column (page 1008-1). 4. Syringe*, 10-µL, readable to 0.1 µL, and 50-µL, readable to 1 µL. 5. Volumetric flasks, 10-mL, 25-mL, and 500 mL. 6. Pipet, 10-mL with pipet bulb.

SPECIAL PRECAUTIONS: Benzene and ethylene dibromide [1] are carcinogens and can be absorbed through the skin. Benzene and methanol are flammable. All work with these should be performed in a hood, while wearing gloves. 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 0.02 and 0.2 L/min for a total sample size of 0.1 to 25 L. Cap the samplers with plastic (not rubber) caps and pack securely in an insulated container with dry ice for shipment.

SAMPLE PREPARATION: NOTE: Store the samplers at -25 °C or below until preparation begins. 5. Place the front and back sorbent sections of the sampler tube in separate 10-mL volumetric flasks. Discard the glass wool and foam plugs. 6. Add 10.0 mL eluent to each flask. 7. Allow to stand 60 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the range 0.01 to 0.5 µg ethylene dibromide per sample. a. Add known amounts of calibration stock solution to eluent in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (ratio of peak area of analyte to peak area of internal standard vs. µg ethylene dibromide). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94