National Institute for Occupational Safety and Health

“ Lift the filter with tweezers above the methanol level and rinse both sides of the filter slowly with two 3-mL aliquots of methanol, collecting the rinse in the beaker. g. Roll and squeeze the filter with tweezers against the inside wall of the beaker to remove methanol retained by the filter. h. Discard the filter. i. Place the beaker on the hot plate (55 °C) and evaporate the methanol to volume less than 5 mL. j. Transfer the methanol extract to a test tube. ”

“ Diethyl ether and pentane are extremely flammable. Boron SAMPLING: trifluoride and pyridine are toxic. Work with these substances only in a hood. 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Connect the filter holder to the pump with a piece of flexible tubing. 3. Sample at an accurately known flow rate between 1.5 and 2 L/min for a total sample size of 400 L or greater. ”

“ Rinse the beaker two or three times with small amounts of methanol and combine the rinsings in the test tube. l. Evaporate the methanol in the test tube to dryness. Derivatization: a. Add 125 μL of BF 3/methanol to each sample or standard tube and screw the cap tightly. ”