|
|
HPLC
|
GC
|
|
Principal
|
Separation
of sample is accomplished by solid stationary phase and liquid mobile phase.
|
Separation
of sample is accomplished by liquid or solid stationary phase and gaseous mobile
phase.
|
|
Temperature
Control
|
Temp.
control approach is not necessary or not required. Generally ambient temp. is
required.
|
Temp.
control is much more important as the column is placed inside the oven with
control temp. program. Generally higher temp. required for analysis.
|
|
Sample
State
|
Separation
of liquid state any soluble samples usually with higher molecular
weight.
|
Separation
of volatile and thermally stable samples with low molecular weight.
|
|
Column
|
Column
are generally shorter and broader diameter.
|
Columns
are long, normally 10 to 60 meters in length and narrow diameter.
|
|
Column
Types
|
Octadecylsilane,
Octyl silane, Hexyl, Trimethyl Silyl, Amino, Cyano, TMS, Silica, Hillic,
Diol, Ion exchange, Chiral, Phenyl, Gel permeation & Size exclusion
chromatography
|
WCOT,
SCOT, PLOT, Carbowax, Polyethylene glycol, Dimethyl polysiloxane, Phenyl
methyl polysiloxane, High molecular mass esters, Amides, Hydrocarbons,
Polyaromatic compound, Cyanopropyl polysiloxane
|
|
Separation
|
Separation
based on the interaction of sample with mobile and stationary phases.
|
Separation
based on the boiling point of sample.
|
|
Resolution
Issues
|
Samples
with identical polarity
|
Samples
with similar molecular weight
|
|
Mobile
Phase
|
Liquids,
e.g. Polar solvents like water, acetonitrile, methanol, etc. Non polar
solvents like Hexane, Heptane, isopropyl alcohol, dichloromethane etc.
|
Gases,
e.g. Nitrogen, Helium, Argon, Hydrogen, Oxygen
|
|
Speed
|
Analysis
speed is slow.
|
Analysis
speed is fast
|
|
Peak
shape
|
Generally,
detect bigger or wider peaks which effect lower resolution.
|
Relatively
sharp peaks observed with good resolution.
|
|
Detectors
|
UV-Visible
detector, Photodiode-array detection, Refractive index detector, light
scattering detector, Charged aerosol detector, Conductivity detector,
Fluorescence detector, Chemiluminescence detector,
Optical rotation detector, Mass spectrometric, IR Detector etc.
|
GC
detectors are sensitive and selective, e.g. Flame ionization detector (FID),
Thermal conductivity detector (TCD), Electrochemical detector, Electron
capture detector, Nitrogen phosphorous detector, Flame photometric detector,
Electrolytic conductivity detector, Mass spectrometric, Photo Ionization
detector, Reduction gas detector, Catalytic combustion detector, Helium
ionization detector etc.
|
|
Cost
|
Less
costly
|
High
cost
|
Comments