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The International System of Units (SI) is used in this Pharmacopeia. The SI metric and other units, and the symbols commonly employed, are as follows.
Bq = becquerel L = liter
kBq = kilobecquerel mL = milliliter,
MBq = megabecquerel µL = microliter
GBq = gigabecquerel Eq = gram-equivalent weight
Ci = curie mEq = milliequivalent
mCi = millicurie mol = gram-molecularweight (mole)
µCi = microcurie Da = dalton (relativemolecular mass)
nCi = nanocurie mmol = millimole
Gy = gray Osmol = osmole
mGy = milligray mOsmol = milliosmole
m = meter Hz = hertz
dm = decimeter kHz = kilohertz
cm = centimeter MHz = megahertz
mm = millimeter V = volts
µm = micrometer(0.001mm) MeV = million electronvolts
nm = nanometer * keV = kilo-electron volt
kg = kilogram mV = millivolt
g = gram ** psi = pounds per square inch
mg = milligram Pa = pascal
µg; mcg = microgram kPa = kilopascal
ng = nanogram g = gravity (incentrifugation)
pg = picogram
fg = femtogram
dL = deciliter
*  Formerly the symbol mµ (for millimicron) was used.
**  The gram is the unit of mass that is used to measure quantities of materials. Weight, which is a measure of the gravitational force acting on the mass of a material, is proportional to, and may differ slightly from, its mass because of the effects of factors such as gravity, temperature, latitude, and altitude. The difference between mass and weight is considered to be insignificant for compendial assays and tests, and the term “weight” is used throughout USP and NF.
  Formerly the abbreviation mcg was used in the Pharmacopeial monographs; however, the symbol µg now is more widely accepted and thus is used in this Pharmacopeia. The term “gamma,” symbolized by , is frequently used for microgram in biochemical literature.
NOTE—The abbreviation mcg is still commonly employed to denote microgram(s) in labeling and in prescription writing. Therefore, for purposes of labeling, “mcg” may be used to denote microgram(s).
  One milliliter (mL) is used herein as the equivalent of 1 cubic centimeter (cc).