Chromatography summary

2 definitions !

1. RO values retardation factor , this is calculated the
using expression :
-




RF = distance moved by spot (value should always be
distance moved by solvent less than 1)

1. Retention time -
the time taken from injection until a component reaches the
detector .




What is
chromatography ?
A
separating technique
·



·
Which allows mixture of soluble chemicals to be separated
Based on their relative solubilities in the mobile phase and the Stationary
phase .

Thin-layer chromatography (TLC) :
Gas-liquid chromatography (GLC)
Mobile phase Mobile He)
liquid gas (inert
-


phase
-
N2 or

solid (silica (SiO)
Stationary phase
or alumina (Al2O3) on flat inert support
-




Stationary phase-liquid on a solid

support (thin layer of alkane in

of plastic or tube)
.
glass. capillary
How separation occurs -

adsorption How separation occurs
-


partition
(adhere to surface) relative
solubility.
M

I
&
N


3 Types of
Chromatography :
stat phase :




mention

- hydrocarbon
liquid/oil held on



Adsorption Paper chromatography : the solid .
support
Mobile phase -



liquid
StationaryPhase-
o as


cellulose in the paper. Partition

&
solid support liquid stationary

#- Stationary support
solid phase solid Phase
The
N A greater the
The stronger
solubility in the
L L
-
dissolve
o N
the adsorption
,
·
stationary phase, the
⑨ /
the more the ⑨
more the component
·
mobile
⑨
component mobile molecules are slowed

Phase molecules are phase down .
· slowed down
.
⑨
⑨
⑨