Page:NIOSH Manual of Analytical Methods - 3513.pdf/2

 TETRANITROMETHANE: METHOD 3513, Issue 1, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2. 3. 4. 5. 6.

EQUIPMENT:

Tetranitromethane. Ethyl acetate, nanograde. Helium, purified. Nitrogen, purified. Hydrogen, purified. Compressed air, filtered.

See SPECIAL PRECAUTIONS.

1. Sampler: midget impinger containing 15 mL ethyl acetate. 2. Personal sampling pump, 0.5 to 1.0 L/min, with flexible connecting tubing and splash over protection. 3. Gas chromatograph, NPD, integrator and column (page 3513-1). 4. Vials, 20-mL, with PTFE screw caps. 5. Syringes, 10-µL, and other convenient sizes. 6. Volumetric flasks, 25-mL, 10-mL.

SPECIAL PRECAUTIONS: Tetranitromethane is highly toxic and extremely explosive [3]. Use fume hood and protective equipment. SAMPLING: 1. 2. 3.

4. 5.

Calibrate each personal sampling pump with a representative sampler inline. Pipette 15 mL of ethyl acetate into each impinger. Attach midget impinger to personal sampling pump with flexible tubing. Sample at an accurately known flow rate of 0.5 to 1.0 L/minute for a total sample size of 20 to 250 L. NOTE: Routinely check and fill impingers to insure that the level of ethyl acetate remains at a volume of 10 to 15 mL. Transfer the sample solution to 20-mL vial. Rinse impinger stem and body with 1 to 2 mL ethyl acetate, and add to the 20-mL vial. Pack securely for shipment.

SAMPLE PREPARATION: 6. 7.

Transfer samples into 25-mL volumetric flasks and dilute to volume with ethyl acetate. Transfer 1 mL aliquot to autosampler vials and immediately cap vials.

CALIBRATION AND QUALITY CONTROL: 8.

9.

Calibrate daily with at least six working standards over the range 17 to 660 µg tetranitromethane per sample. a. Add known amounts of tetranitromethane to ethyl acetate in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 10 and 11). c. Prepare calibration graph (peak area vs. µg tetranitromethane). Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph is in control.

MEASUREMENT: 10.

Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 3513-1. Inject 1-µL sample aliquot manually using solvent flush technique or with autosampler. NOTE: If peak area is above the linear range of the working standards, dilute with ethyl acetate, NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94