Page:NIOSH Manual of Analytical Methods - 6015.pdf/5

 AMMONIA: METHOD 6015, Issue 2, dated 15 August 1994 - Page 5 of 7 APPENDIX: PREPARATION OF SULFURIC ACID-TREATED SILICA GEL 1.

Place 6 g of 20/40 mesh silica gel in 250-mL beaker.

2.

Add 15 mL 0.4 N sulfuric acid to the beaker. Stir the mixture, and cover the beaker with a watch glass.

3.

Heat the silica gel-acid mixture in a fume hood with a Bunsen burner to a very gentle boil. Evaporate approximately one-half of the liquid.

4.

Place the covered beaker in a drying oven at 120 °C until the remainder of the water has been evaporated.

5.

The prepared acid-treated silica gel should flow freely and not adhere to the beaker. Store in silica gel in a desiccator until ready for use.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94