National Institute for Occupational Safety and Health

“ Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and DE graph are in control.
MEASUREMENT: 12.
13.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1457-1. Inject 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 CS 2, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area. ”

“ Add 1.0 mL CS 2 to each vial. Attach crimp cap to each vial. NOTE: Decane or other suitable internal standard at 0.1% v/v may be added at this step. Allow to stand 30 min with occasional agitation.
CALIBRATION AND QUALITY CONTROL: 8.
Calibrate daily with at least six working standards over the range 8 to 1000 μg analyte per sample. a. Add known amounts of analyte to CS 2 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 (peak area of analyte vs. mg ethyl acetate) . ”

“ Determine desorption efficiency (DE) at least once for each lot of charcoal used for sampling in the calibration range (step 8) . Prepare three tubes at each of five concentrations plus three media blanks. Determine desorption efficiency (DE) for each lot of charcoal tubes used for sampling in the calibration range (step 9) . a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount of calibration stock solution directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. ”