National Institute for Occupational Safety and Health

“ Handle all hazardous chemicals in a fume hood.
SAMPLING: 1. 2. 3. 4.
Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach a sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.05 and 0.2 L/min for total volume of 1 to 24 L. Cap the tubes with plastic (not rubber) caps, plug filter cassettes, and pack securely for shipment. NOTE: Prefilters may be analyzed for particulate formates, or may be discarded.
SAMPLE PREPARATION: 5. ”

“ The solution must be prepared fresh daily. Loss of formic acid was observed after 24 h. Pipetting below the liquid level of the standard will minimize loss of formic acid from evaporation. APPENDIX B: SAMPLING TUBE PREPARATION Silica gel cleaning procedure: Add 500 to 600 mL deionized water, slowly and with stirring, to ca. 200 mL volume of silica gel in 1-L beaker. When exothermal reaction has subsided, heat in boiling waterbath for ca. ”