Gas Chromatography (GC) (IUPAC Compendium of Chemical Terminology):

Lecture 3. Gas chromathography.
Intermediate polarity to strongly polar stationary phases.
BONDED PHASE Temp °C GENERAL USE OF PHASE
Methyl 7% Cyanopropyl 7%
Phenyl Polysiloxane
CN
CH 3
* O Si O Si *
X
CH 3
Y
280
Intermediate polarity.
Unique selectivity of cyanopropyl and phenyl
groups provide efficient separations of
derivitized sugars and many environmental
samples. Not truly a polar phase. Good thermal
stability
Methyl 25% Cyanopropyl 25%
Phenyl Polysiloxane
CN
CH 3
* O Si O Si *
X
CH 3
Y
40-240
Polar. Optima 225
Provides efficient separations of polar
molecules such as fatty acids and alditol
acetate derivatives of sugars. Fair thermal
stability.
50% Trifluoropropyl 50% Methyl
polysiloxane
*
CF 3
CH 3
Si O Si
Y
X
*
CH 3
CF 3
Polyethylene Glycol
* CH 2
CH 2
O *
n
40-300
20-260
Polar. Optima 210
Selectivity for compounds with lone pair
electrons or carbonyl groups. Retains
oxygenated compounds in the order ether,
hydroxy, ester and keto Widely used as a
confirmatory phase for chlorinated pesticides.
Also suitable for PCB’s, phenols and
nitroaromatics. Good thermal stability.
Carbowax 20M is a polyethylene glycol phase
which demonstrates unique selectivity
hydrogen bonding-type molecules. Particularly
useful for the analysis of complex oxygenated
samples but is susceptible to oxygen
degradation. Not recommended for the
analysis of mixtures containing silylating
reagents
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