Pumice
» 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%).
Iron— Acidify the remaining half of the filtrate from the test for Water-soluble substances with hydrochloric acid, and add a few drops of potassium ferrocyanide TS: no blue color is produced.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Senior Scientist
1-301-816-8251
(MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
USP32–NF27 Page 3445
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.