National Institute for Occupational Safety and Health

“ Prepare calibration graph (ratio of peak area of analyte to peak area of internal standard vs. mg naphtha) . Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibration range (step 8) . Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount of naphtha bulk sample directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. ”

“ METHOD 1550, Issue 2, dated 15 August 1994 - Page 2 of 5 REAGENTS: 1.
2. 3. 4. 5.
EQUIPMENT:
Eluent: Carbon disulfide*, chromatographic quality, containing 0.1% (v/v) octane, 0.5% (v/v) hexadecane or other suitable internal standard. NOTE 1: Use an internal standard which is not a major constituent of the sample. NOTE 2: Use toluene in place of carbon disulfide for low-boiling analytes [5] . Naphtha bulk sample. Nitrogen or helium, purified. Hydrogen, prepurified. Air, filtered. ”

“ Carbon disulfide is toxic and an acute fire and explosion hazard (flash point = -30 °C) ; work with it only in a hood.
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 which contains between 0.5 and 8 mg naphtha. ”