National Institute for Occupational Safety and Health

“ Add known amounts of calibration stock solution to 10-mL volumetric flasks and dilute to volume with 5% HCl/1.1 mg/mL Na + solution to produce Ba 2+ concentrations in the range 0.4 to 40 μg/mL (0.002 to 0.2 mg per sample) . Prepare fresh daily. Analyze working standards with the blanks and samples (steps 17 and 18) . Prepare calibration graph (absorbance vs. solution concentration, μg/mL) . Aspirate a standard for every ten samples to check instrument drift. Check recoveries with at least one spiked media blank per ten samples. ”

“ Rinse original beaker three times with ca. 2 mL hot distilled water and add to centrifuge tube. Centrifuge and decant the solution to a second beaker. Add three drops conc. HCl to sample and evaporate until ca. 0.5 mL liquid remains. Cool each beaker. Pipet 5.0 mL 5% HCl/1.1 mg/mL Na + solution into each beaker. Swirl to dissolve residue.
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition, 8/15/94 BARIUM, soluble compounds: METHOD 7056, Issue 2, dated 15 August 1994 - Page 3 of 3 CALIBRATION AND QUALITY CONTROL: 11. ”

“ HNO 3 and rinse thoroughly with distilled or deionized water before use.
SPECIAL PRECAUTIONS: Nitric and hydrochloric acids are corrosive liquids. Wear protective clothing and work in a fume head. SAMPLING: 1. ”