National Institute for Occupational Safety and Health

“ TECHNIQUE: GRAVIMETRIC (FILTER WEIGHT)
ANALYTE: airborne particulate material
BALANCE: 0.001 mg sensitivity; use same balance before and after sample collection
CALIBRATION: National Institute of Standards and Technology Class S-1.1 weights or ASTM Class 1 weights
RANGE: 0.1 to 2 mg per sample
ESTIMATED LOD: 0.03 mg per sample
PRECISION (S1) :0.026 [2]
APPLICABILITY: The working range is 1 to 20 mg/m3 for a 100-L air sample. This method is nonspecific and determines the total dust concentration to which a worker is exposed. ”

“ PREPARATION OF FILTERS BEFORE SAMPLING:
Equilibrate the filters in an environmentally controlled weighing area or chamber for at least 2 h.
NOTE: An environmentally controlled chamber is desirable, but not required. Number the backup pads with a ballpoint pen and place them, numbered side down, in filter cassette bottom sections. Weigh the filters in an environmentally controlled area or chamber. Record the filter tare weight, W1 (mg) . Zero the balance before each weighing. Handle the filter with forceps. Pass the filter over an antistatic radiation source. ”

“ Static electricity can cause erroneous weight readings. Assemble the filter in the filter cassettes and close firmly so that leakage around the filter will not occur. Place a plug in each opening of the filter cassette. Place a cellulose shrink band around the filter cassette, allow to dry and mark with the same number as the backup pad. SAMPLING:
Calibrate each personal sampling pump with a representative sampler in line. Sample at 1 to 2 L/min for a total sample volume of 7 to 133 L. Do not exceed a total filter loading of approximately 2 mg total dust. ”