» Pumice is a substance of volcanic origin, consisting chiefly of complex silicates of aluminum, potassium, and sodium.
Packaging and storage Preserve in well-closed containers.
Labeling Label powdered Pumice to indicate, in descriptive terms, the fineness of the powder.
Powdered Pumice Meets the following requirements:
Pumice Flour or Superfine Pumice: not less than 97.0% of pumice flour or superfine pumice passes through a No. 200 standard mesh sieve.
Fine Pumice: not less than 95.0% of fine pumice passes through a No. 150 standard mesh sieve and not more than 75.0% passes through a No. 200 standard mesh sieve.
Coarse Pumice: not less than 95.0% of coarse pumice passes through a No. 60 standard mesh sieve and not more than 5.0% passes through a No. 200 standard mesh sieve.
Water-soluble substances Boil 10 g with 50 mL of water for 30 minutes, adding water from time to time to maintain approximately the original volume, and then filter: the filtrate is neutral to litmus, and one-half of this filtrate, when evaporated and dried at 105 for 1 hour, yields not more than 10 mg of residue (0.20%).
Acid-soluble substances Boil 1 g of Pumice with 25 mL of 3 N hydrochloric acid for 30 minutes, adding water from time to time to maintain approximately the original volume, then filter the liquid. Add 5 drops of sulfuric acid to the filtrate, evaporate to dryness, ignite, and weigh the residue: not more than 60 mg of residue is obtained (6.0%).
Auxiliary Information Please check for your question in the FAQs before contacting USP.Chromatographic Column
USP32NF27 Page 3445
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.