8. TERMS AND DEFINITIONS
8.10. Abbreviations
  • RS refers to a USP Reference Standard.
  • CS refers to a Colorimetric Solution.
  • TS refers to a Test Solution.
  • VS refers to a Volumetric Solution that is standardized in accordance with directions given in the individual monograph or in the Reagents, Indicators, and Solutions section of USP–NF.
8.20. About
“About” indicates a quantity within 10%.
If the measurement is stated to be “accurately measured” or “accurately weighed,” follow the statements in the general chapters Volumetric Apparatus 31 and Weights and Balances 41, respectively.
8.30. Alcohol Content
Percentages of alcohol, such as those under the heading Alcohol content, refer to percentage by volume of C2H5OH at 15.56. Where a formula, test, or assay calls for alcohol, ethyl alcohol, or ethanol, the USP monograph article Alcohol shall be used. Where reference is made to “C2H5OH,” absolute (100 percent) ethanol is intended. Where a procedure calls for dehydrated alcohol, alcohol absolute, or anhydrous alcohol, the USP monograph article Dehydrated Alcohol shall be used.
8.40. Atomic Weights
Atomic weights used in computing molecular weights and the factors in the assays and elsewhere are those established by the IUPAC Commission on Atomic Weights and Isotopic Abundances.
8.50. Blank Determinations
Where it is directed that “any necessary correction” be made by a blank determination, the determination shall be conducted using the same quantities of the same reagents treated in the same manner as the solution or mixture containing the portion of the substance under assay or test, but with the substance itself omitted.
8.60. Concomitantly
“Concomitantly” denotes that the determinations or measurements are to be performed in immediate succession.
8.70. Desiccator
The instruction “in a desiccator” indicates use of a tightly closed container of suitable size and design that maintains an atmosphere of low moisture content by means of a suitable desiccant such as anhydrous calcium chloride, magnesium perchlorate, phosphorus pentoxide, or silica gel. See also section 8.220, Vacuum Desiccator.
8.80. Logarithms
Logarithms are to the base 10.
8.90. Microbial Strain
A microbial strain cited and identified by its ATCC catalog number shall be used directly or, if subcultured, shall be used not more than five passages removed from the original strain.
8.100. Negligible
“Negligible” indicates a quantity not exceeding 0.50 mg.
8.110. NLT/NMT
“NLT” means “not less than.” “NMT” means “not more than.”
8.120. Odor
“Odorless,” “practically odorless,” “a faint characteristic odor,” and variations thereof indicate evaluation of a suitable quantity of freshly opened material after exposure to the air for 15 minutes. An odor designation is descriptive only and should not be regarded as a standard of purity for a particular lot of an article.
8.130. Percent
“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;
  • 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.
8.140. Percentage Concentrations
Percentage concentrations are expressed as follows:
  • Percent Weight in Weight (w/w) is defined as the number of g of a solute in 100 g of solution.
  • Percent Weight in Volume (w/v) is defined as number of g of a solute in 100 mL of solution.
  • Percent Volume in Volume (v/v) is defined as the number of mL of a solute in 100 mL of solution.
8.150. Pressure
Pressure is determined by use of a suitable manometer or barometer calibrated in terms of the pressure exerted by a column of mercury of the stated height.
8.160. Reaction Time
Reaction time is 5 minutes unless otherwise specified.
8.170. Specific Gravity
Specific gravity is the weight of a substance in air at 25 divided by the weight of an equal volume of water at the same temperature.
8.180. Temperatures
Temperatures are expressed in centigrade (Celsius) degrees, and all measurements are made at 25 unless otherwise indicated. Where moderate heat is specified, any temperature not higher than 45(113 F) is indicated.
8.190. Time
Unless otherwise specified, rounding rules, as described in section 7.20, Rounding Rules, apply to any time specified.
8.200. Transfer
“Transfer” indicates a quantitative manipulation.
8.210. Vacuum
“Vacuum” denotes exposure to a pressure of less than 20 mm of mercury (2.67 kPas), unless otherwise indicated.
8.220. Vacuum Desiccator
“Vacuum desiccator” indicates a desiccator that maintains a low-moisture atmosphere at a reduced pressure of not more than 20 mm of mercury (2.67 kPas) or at the pressure designated in the individual monograph.
8.230. Water
8.230.10. Water as an Ingredient in an Official Product
As an ingredient in an official product, water meets the requirements of the appropriate water monograph in USP or NF.
8.230.20. Water in the Manufacture of Official Substances
When used in the manufacture of official substances, water may meet the requirements for drinking water as set forth in the regulations of the U.S. Environmental Protection Agency (potable water).
8.230.30. Water in a Compendial Procedure
When water is called for in a compendial procedure, the USP article Purified Water shall be used unless otherwise specified. Definitions for High-Purity Water and Carbon Dioxide–Free Water are provided in Containers—Glass 660. Definitions of other types of water are provided in Water for Pharmaceutical Purposes 1231.
8.240. Weights and Measures
In general, weights and measures are expressed in the International System of Units (SI) as established and revised by the Conférence générale des poids et mesures. For compendial purposes, the term “weight” is considered to be synonymous with “mass.”
Molality is designated by the symbol m preceded by a number that represents 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 represents the number of moles of the designated solute contained in an amount of the designated solvent that is sufficient to prepare 1 liter of solution.
Normality is designated by the symbol N preceded by a number that represents the number of equivalents of the designated solute contained in an amount of the designated solvent that is sufficient to prepare 1 liter of solution.
Symbols commonly employed for SI metric units and other units are as follows:
Bq = becquerel dL = deciliter
kBq = kilobecquerel L = liter
MBq = megabecquerel mL = milliliterc
GBq = gigabecquerel µL = microliter
Ci = curie Eq = gram-equivalent weight
mCi = millicurie mEq = milliequivalent
µCi = microcurie mol = gram-molecular weight (mole)
nCi = nanocurie Da = dalton (relative molecular mass)
Gy = gray mmol = millimole
mGy = milligray Osmol = osmole
m = meter mOsmol = milliosmole
dm = decimeter Hz = hertz
cm = centimeter kHz = kilohertz
mm = millimeter MHz = megahertz
µm = micrometer (0.001mm) V = volts
nm = nanometera MeV = million electron volts
kg = kilogram keV = kilo-electron volt
g = gram mV = millivolt
mg = milligram psi = pounds per square inch
µg; mcg = microgramb Pa = pascal
ng = nanogram kPa = kilopascal
pg = pictogram g = gravity (in centrifugation)
fg = femtogram
a  Previously the symbol mµ (for millimicron) was used.
b  One milliliter (mL) is used herein as the equivalent of one cubic centimeter (cc).
c  The symbol µg is used in the USP and NF to represent micrograms, but micrograms may be represented as “mcg” for labeling and prescribing purposes. The term “gamma,” symbolized by , frequently is used to represent micrograms in biochemical literature.