Page:NIOSH Manual of Analytical Methods - 2526.pdf/2

 NITROETHANE: METHOD 2526, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1.

2. 3. 4. 5.

6. 7. 8.

EQUIPMENT:

Eluent: Ethyl acetate, containing (optionally) 0.1% v/v 1-hexanol or other suitable internal standard. Nitroethane, chromatographic quality.* Methanol. Methylene chloride.* Calibration stock solution, 0.21 mg/µL. Add 2.1 g (2.0 mL) nitroethane to a 10-mL volumetric flask. Dilute to the mark with ethyl acetate. Helium or nitrogen, purified. Hydrogen, prepurified. Air, filtered.



See SPECIAL PRECAUTIONS.

1. Sampler: separate front and backup glass tubes with plastic caps, each 10 cm long, 10-mm OD, 8-mm ID, flame-sealed ends, packed with 20/50 mesh XAD-2 (front = 600 mg; back = 300 mg). The sorbent beds are held in place with silanized glass wool plugs. Pressure drop across the tubes at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available (SKC Cat. No. 226-3002, or equivalent). 2. Personal sampling pump, 0.01 to 0.05 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator and column (page 2526-1). 4. Vials, glass, 5-mL, PTFE-lined crimp caps. 5. Syringes, 2- to 20-µL, readable to 0.1 µL. 6. Volumetric flask, 10-mL. 7. Pipets, delivery-type, 1- and 2-mL; calibrated-type, 5-mL, readable to 0.01 mL. 8. File.

SPECIAL PRECAUTIONS: Contact with amines, strong acids, and alkalies may sensitize nitroethane so that it will readily explode [3]. Methylene chloride is a suspect carcinogen.

SAMPLING: 1. 2. 3.

4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler tubes immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.05 L/min for a total sample size of 1.5 to 3 L. NOTE: High pressure drop across the sampler may occur at flow rates above 0.05 L/min, giving inaccurate sample volumes. Immediately following sampling, separate the front from the back sorbent tube and cap both. Pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler in separate vials. Discard the glass wool plugs. Pipet 2.0 mL eluent into each vial. Cap each vial. 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 to eluent in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain nitroethane concentrations in the range 0.03 to 1 mg/mL. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94