National Institute for Occupational Safety and Health

“ SAMPLING: 1. 2. 3. 4. 5.
Calibrate each personal sampling pump with a representative sampler in line. Break ends of tubes immediately before sampling. Attach filter cassette to inlet of XAD-2 tube with short piece of tubing. Connect the outlet of sampler to pump. Sample at an accurately known flow rate between 0.2 and 1 L/min for a total sample size of 30 to 500 L. Transfer the filter, the front glass wool plug, and the front sorbent section to the same vial. ”

“ NOTE: If peak area is above the linear range of the working standards, dilute with toluene, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.
CALCULATIONS: 14.
15.
Determine the mass, μg (corrected for DE) of Demeton (sum of Demeton O and Demeton S) found on the sample filter plus front sorbent section (W + W f) , back (W b) sorbent section, and on the average media blank filter (B) and front (B f) and back (B b) media blank sorbent sections. ”

“ Calibrate daily with at least six working standards over the range 0.1 to 100 μg Demeton per sample for each isomer. a. Add known amounts of calibration stock solution to toluene in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 12 and 13) . c. Prepare calibration graph (peak area vs. μg of each isomer) . Determine desorption efficiency (DE) at least once for each lot of XAD-2 used for sampling in the calibration range (step 9) . Prepare three tubes at each of five levels plus three media blanks. a. ”