National Institute for Occupational Safety and Health

“ Calibrate daily with at least six working standards over the range of interest. a. Make serial dilutions as needed to obtain MDA concentrations in the range 0.025 to 1 μg/mL. b. Analyze together with samples and blanks (steps 11 through 13) . c. Prepare a calibration graph (peak area vs. concentration of MDA, μg per sample) for each detector (UV and ECHD) . Determine the recovery at least once for each lot of filters used for sampling in the range of interest. Prepare six filters at each of three concentration levels plus three media blanks. ”

“ WIPE SAMPLING-This analytical method was used to analyze environmental samples collected on gauze pads and smear tabs. MDA was spiked onto acid-treated gauze pads, plain gauze pads, and smear tabs at 92, 9.2, and 0.92 μg per sample. Sets of each concentration were extracted immediately after allowing the spiking solution to evaporate, one day, one week, and one month after spiking. The extraction solution consisted of 10 mL 0.1 N methanolic KOH for the gauze pads and 2 mL for the smear tabs. The best recovery was obtained when the media were extracted immediately after the methanol evaporated. ”

“ Prepare filter by adding 0.5 mL 0.26 N sulfuric acid to glass fiber filter on a glass tray. Heat for 1 hour at 100 °C. Load the filter, backed by a paper O-ring, into a cassette and seal with shrink band to enable open-face sampling. 2. Personal sampling pump, 1 to 2 L/min, with flexible tubing. ”