National Institute for Occupational Safety and Health

“ Add 200 mL toluene and swirl the mixture. Allow the flask to stand for 1 hour. Remove the toluene using rotary evaporation. If the last traces of toluene are difficult to remove, add about 100 mL of methanol to the flask, swirl the mixture and then remove the solvents using rotary evaporation. XAD-2 adsorbent treated in this manner will often contain residual formaldehyde derivative levels of about 0.1 μg/150 mg of adsorbent. The formaldehyde blank level and potential acrolein and acetaldehyde chromatographic interferences should be determined at this time. ”

“ Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph is in control. NOTE: A desorption efficiency study is not usually necessary since standards are prepared on the coated sorbent.
MEASUREMENT: 10.
11.
Set gas chromatograph to conditions given on page 2538-1. Set air and hydrogen flows on the flame ionization detector to manufacturer's specifications. Inject 1-μL sample aliquot via the splitless injection technique. Retention time = 6.8 min for acetaldehyde under these conditions. Measure peak area. ”

“ Immediately pipet 1.0 mL of acetaldehyde into the cold flask, reseal the flask and allow it to warm to room temperature. e. Reweigh the flask and subtract the tare weight from the weight of the reweighed flask to determine the weight of acetaldehyde added. f. Dilute the contents of the flask to the mark with toluene. g. Store the stock standards in a freezer. Prepare fresh stock standards every 10 days. APPENDIX B: PREPARATION OF XAD-2 SORBENT COATED WITH 2-HMP Weigh 125 g of crude XAD-2 adsorbent into a 1-L Erlenmeyer flask. ”