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CONCENTRATIONS Molal, molar, and normal solution concentrations are indicated throughout this Pharmacopeia for most chemical assay and test procedures (see also Volumetric Solutions in the section Reagents, Indicators, and Solutions). Molality is designated by the symbol m preceded by a number that is the number of moles of the designated solute contained in 1 kilogram of the designated solvent. Molarity is designated by the symbol M preceded by a number that is the number of moles of the designated solvent. Molarity is designated solute contained in an amount of the designated solvent that is sufficient to prepare 1 L of solution. Normality is designated by the symbol N preceded by a number that is the number of equivalents of the designated solute contained in an amount of the designated solvent that is sufficient to prepare 1 L of solution. Percentage Measurements—Percentage concentrations are expressed as follows: Percent Weight in Weight—(w/w) expresses the number of g of a constituent in 100 g of solution or mixture. Percent Weight in Volume—(w/v) expresses the number of g of a constituent in 100 mL of solution, and is used regardless of whether water or another liquid is the solvent. Percent Volume in Volume—(v/v) expresses the number of mL of a constituent in 100 mL of solution. The term percent used without qualification means, for mixtures of solids and semisolids, percent weight in weight; for solutions or suspensions of solids in liquids, percent weight in volume; for solutions of liquids in liquids, percent volume in volume; and for solutions of gases in liquids, percent weight in volume. For example, a 1 percent solution is prepared by dissolving 1 g of a solid or semisolid, or 1 mL of a liquid, in sufficient solvent to make 100 mL of the solution. In the dispensing of prescription medications, slight changes in volume owing to variations in room temperatures may be disregarded.. VEGETABLE AND ANIMAL SUBSTANCES The requirements for vegetable and animal substances apply to the articles as they enter commerce; however, lots of such substances intended solely for the manufacture or isolation of volatile oils, alkaloids, glycosides, or other active principles may depart from such requirements. Statements of the distinctive microscopic structural elements in powdered substances of animal or vegetable origin may be included in the individual monograph as a means of determining identity, quality, or purity. Foreign Matter—vegetable and animal substances are to be free from pathogenic organisms (see Microbiological Attributes of Nonsterile Pharmaceutical products 1111), and are to be as free as reasonably practicable from microorganisms, insects, and other animal contamination, including animal excreta. They shall show no abnormal discoloration odor, sliminess, or other evidence of deterioration. The amount of foreign inorganic matter in vegetable or animal substances, estimated as Acid-insoluble ash shall not exceed 2 percent of the weight of the substance, unless otherwise specified in the individual monograph. Before vegetable substances are ground or powdered, stones, dust, lumps of soil, and other foreign inorganic matter are to be removed by mechanical or other suitable means. In commerce it is seldom possible to obtain vegetable substances that are without some adherent or admixed, innocuous, foreign matter, which usually is not detrimental. No poisonous, dangerous, or otherwise noxious foreign matter or residues may be present. Foreign matter includes any part of the plant not specified as constituting the substance. Preservation—Vegetable or animal substances may be protected from insect infestation or microbiological contamination by means of suitable agents or processes that leave no harmful residues. | 
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发表于 14-1-22 16:14:06
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