Getting Started in HPLC

Section 0. The Language of HPLC: A

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

   
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.


 
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!


   
ACETONITRILE: one of three organic solvents commonly used (with water) to prepare reversed-phase mobile phases (see also METHANOL and TETRAHYDROFURAN).


 
ADSORPTION CHROMATOGRAPHY: another HPLC method, different from reversed-phase chromatography. Also called LIQUID-SOLID CHROMATOGRAPHY. Typically considered a type of NORMAL-PHASE CHROMATOGRAPHY.


 
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.


 
ANALYTE: the compound to be analyzed. Sometimes referred to as the "unknown".


 
ANALYTICAL COLUMN: the main column used in the HPLC system to separate and analyze samples.


 
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


   
ARCHIVING: refers to the long-term storage of chromatograms or derived data, usually in a computer database or LIMS (Laboratory Information Management System).


 
ATMOSPHERE: a unit of pressure equal to about 15 pounds per square inch; also called a "bar". To be more precise, 1atm =
  • 14.696 psi
  • 1.013 bar
  • 0.1013 megapascals (MPa)

For a handy pressure conversion utility, check out the Well Engineering and Construction web site.


 
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.


 
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).


 
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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Last revised: April 02, 2001.