Getting Started in HPLC

Section 0. The Language of HPLC: S

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

   
SENSITIVITY: generally refers to DETECTOR SENSITIVITY, the ability of the detector to give larger bands (other factors equal) and a better signal-to-noise ratio. This provides more precise analysis of very small sample concentrations.


 
SEPARATION FACTOR (a): defined for two adjacent bands as the ratio of k' for the second band divided by k' for the first band; when the separation factor equals 1.00, the two bands are on top of each other and completely unseparated. Changing the experimental conditions can increase a and permit the two bands to be separated. Also sometimes called RELATIVE RETENTION.


The separation factor is a measure of the selectivity of a separation.


   
SERIAL NUMBER: refers to the identification number of a column, part, module or LC system; used to identify a particular item so that it is not confused with a similar item.


 
SILICA: a glasslike material used to make the particles of column packing. Its chemical formula is Si02.


 
SINKER: the inlet filter that connects to the end of the line that feeds mobile phase to the LC pump. Also serves to weight the inlet line to keep it at the bottom of the reservoir.


 
SIZE-EXCLUSION CHROMATOGRAPHY (SEC): another HPLC method, different from reversed-phase chromatography. Size-exclusion chromatography is used mainly to separate high-molecular-weight samples and to determine their molecular weight or molecular-weight distribution. Also called GEL FILTRATION (GFC) or GEL PERMEATION CHROMATOGRAPHY (GPC).


 
SOLVENTS: the pure components of the mobile phase (e.g., water, methanol, acetonitrile). In reversed-phase chromatography, water is a WEAK SOLVENT, so mobile phases with higher concentrations of water are weaker and give longer retention times for all sample bands. Methanol is a STRONG SOLVENT, so increasing the amount of methanol in the mobile phase makes it stronger, and sample bands leave the column sooner.


 
SPARGING: refers to bubbling a gas (usually helium) through the mobile phase to drive out dissolved air. See Degassing.


Helium sparging is one of the most effective ways of removing dissolved gas from the mobile phase.


   
STANDARD: a sample with a known concentration of some compound X that is to be determined by an LC procedure. The concentration of X in a sample is determined by comparing its peak size with the peak size of the standard. Also called the CALIBRATOR.


 
STATIONARY PHASE: the particulate material packed inside the column; also, the bonded phase that is part of the column packing.


 
STRONG SOLVENT or MOBILE PHASE: a strong mobile phase is one that gives shorter retention times for all sample bands; in reversed-phase chromatography, methanol and acetonitrile are strong solvents, and water is a weak solvent. Mobile phases with more methanol or acetonitrile will be stronger than mobile phases with more water. So 80% methanol/water is a stronger mobile phase than 20% methanol/water.


 
   
 

 


2000, LC Resources Inc. All rights reserved.
Last revised: April 02, 2001.