National Institute for Occupational Safety and Health

“ Add known amounts of calibration stock solution to solvent in 10-mL volumetric flasks and dilute to the mark. Prepare additional standards by serial dilution. Prepare fresh daily. b. Analyze together with samples and blanks (steps 11 and 12) . c. Prepare calibration graph (peak area or height vs. μgN-methyl-2-pyrrolidinone) . 9. Determine desorption efficiency (DE) at least once for each lot of charcoal tubes used for sampling in the calibration range (step 8) . ”

“ Calibration Stock Solution. Add N-methyl-2-pyrrolidinone to desorption solvent in a 10-mL volumetric flask. Protect from light.
See SPECIAL PRECAUTIONS SPECIAL PRECAUTIONS: N-methyl-2-pyrrolidinone is an irritant with possible teratogenic properties. Methanol is flammable and a dangerous fire risk. Methylene chloride is a potential occupational carcinogen. Wear appropriate protective clothing and work with these compounds in a well ventilated hood.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break ends of tubes immediately before sampling. ”

“ Inject a 1-μL sample aliquot manually using solvent flush technique or with an autosampler. NOTE: If peak area is above the linear range of the working standards, dilute with desorption solvent, reanalyze, and apply the appropriate dilution factor in the calculations. Measure peak areas.
CALCULATIONS: 13.
14.
Determine the mass, μg (corrected for DE) , forN-methyl-2-pyrrolidinone found in the sample front (Wf) and back (Wb) sorbent sections, and in the average media blank front (B f) and back (Bb) sorbent sections. NOTE: If Wb > Wf/10, report breakthrough and possible sample loss. ”