National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)
“ Calibrate daily with at least six working standards over the range 0.005 to 1 μg Be per sample. a. Use serial dilutions of known amounts of calibration stock solution in 2% Na 2SO 4/ 3% H 2SO 4 to prepare working standards. Store in polyethylene bottles. Stable at least four weeks. b. Analyze together with samples and blanks (steps 11 and 12) . NOTE: Analyze working standards alternately with the samples to compensate for the increasing Be signal as the graphite tube ages. Analyze three quality control blind spikes and three analyst spikes. ”
