| ABSORBANCE: a
measure of the amount of light taken up by or "absorbed"
by the liquid (the mobile phase and/or the sample components)
passing through the detector cell.
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| ACCURACY: the
extent to which values obtained by LC analysis are
centered around the "true" value (the extent to
which there is no bias in the LC method). See also PRECISION.
|
 Accuracy and Precision are not the same thing!
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| ACETONITRILE: one
of three organic solvents commonly used (with water) to
prepare reversed-phase mobile phases (see also METHANOL and TETRAHYDROFURAN).
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| ADSORPTION
CHROMATOGRAPHY: another HPLC method, different
from reversed-phase chromatography. Also called LIQUID-SOLID
CHROMATOGRAPHY. Typically considered a type of NORMAL-PHASE
CHROMATOGRAPHY.
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| AIR BATH: a
compartment (part of an LC system) where the column is
located and in which the temperature is controlled (kept
constant) by flow of thermostatted air.
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| ANALYTE: the
compound to be analyzed. Sometimes referred to as the
"unknown".
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| ANALYTICAL
COLUMN: the main column used in the HPLC system to separate
and analyze samples.
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| ASYMMETRY FACTOR (As)
or PEAK ASYMMETRY: a measure of how much a band deviates
from being perfectly bell-shaped or symmetrical;
calculated as shown here. See also TAILING
FACTOR. In most
cases, the Asymmetry Factor and Tailing Factor for a peak
will be of similar magnitude, but only rarely are they
exactly equal.
|
 The Asymmetry Factor is one way of describing tailing
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| ARCHIVING: refers
to the long-term storage of chromatograms or derived data,
usually in a computer database or LIMS (Laboratory
Information Management System).
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ATMOSPHERE: a unit
of pressure equal to about 15 pounds per square inch;
also called a "bar". To be more precise, 1atm =
For a handy pressure conversion utility, check out the Well Engineering and Construction web site.
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| ATTENUATION: a
detector setting that increases or decreases band size to
allow peaks to fit within the working range of the data
system display. Also called SENSITIVITY or RANGE.
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| AUFS or ABSORBANCE
UNITS FULL SCALE: refers to the attenuation of the UV
detector for a
particular run. A reading of 0.1 AUFS means that a 100%
reading on the data system display corresponds to an
absorbance of the column effluent equal to 0.1 absorbance
unit. In some cases, 0.001 AUFS will be expressed as
"1 milliAbsorbance Units Full Scale" (1 mAUFS).
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| AUTOSAMPLER: an
HPLC module that automatically injects samples into the
LC system; an autosampler allows samples stored in sealed
vials to be placed on a turntable that feeds the sample injector.
|
 Alcott 718 Autosampler
|
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