Gas ChromatographyCompiled by : Imanuelle Orchidea
3325102413
Definition • A chromatographic technique in which the
mobile phase is a gas
Gas
Liquid
Solid
Gas –Liqui
d/ Gas-Solid Chromatograph
y
perekam
Tabu
ng g
as
Rangkaian penghubung &
penguat
Mobile phase
• Inert gas ( He, Ar, N2)• Carry the sample• Flow rates determined with a flow meter
placed at a column outlet
Column type Flow rate
Packed column 25-150 mL/min
Capillary column 1-25 mL/min
Chromatographic Columns
Packed columns
Capillary columns
Packed Columns
– Glass/stainless steel/copper/aluminum– 2-6 m in length, internal Ø 2-4mm– Particle Ø ranging from 37-44 µm to 250-354 µm– diatomaceous earth, glass beads, fluorocarbons
polymers– Handle larger samples– Pressure needed to move mobile phase limits it’s
length
Capillary Columns
• Open tubular column– Wall-coated– Support-coated
• Fused silica coated with protective polymer• Up to 100 m in length• Internal Ø 150-300 µm, megabore up to 530
µm• Handle smaller samples ( < 10-2 µL)
• Photo of capillary column, taken from Harvey, David .T. Modern Analytical Chemistry
Stationary phase• Choice of stat. phase selectivity• Criteria :
– CHEMICALLY INERT– THERMALLY STABLE– LOW VOLATILITY– APPROPRIATE POLARITY
• R – SiR2 – O - (SiR2 – O)n – SiR3
• HO – CH2 – CH2 – (O – CH2 – CH2)n – OH
STAT.PHASE POLARITY TRADE NAME (T)LIMIT APPLICATIONS
Squalane Non-polar Squalane 150 Low boiling aliphatic hydrocarbons
Apezion L Non-polar Apezion L 300 AmidesFatty acid methyl estersHigh boiling aliphatic HC
TerpenoidsPolydimethyl
siloxaneSlightly SE-30 300-350 Alkaloids*
Amino acid derivatives ** Drugs# pesticides##
Phenols & steroids50% methyl-50%phenyl
polysiloxane
Moderate OV-17 375 *, #, ##, Polyaromatic hydrocarbons
Polychlorinated biphenyls50%TFP-
50%MPSOModerate OV-210 275 *,**, #, halogenated compounds,
ketones, phenols50% CYP-50% phe-me-PSO
Polar OV-225 275 Nitriles, pesticides, steroids
PEG Polar Carbowax 20M
225 Aldehydes, esters, ethers, phenols
Introduction of samples
1. All constituents must be volatile2. Appropriate concentration3. Must not degrade the separation
Volatile analyte from Non volatile matrix:1. Liquid-liquid extraction2. Solid phase extraction SPME3. Headspace sampling4. Cryogenic focusing
Injecting the sample
• Split injection• Splitless injection• On-column injection
Schematic diagram of an injector for packed column GC
Detectors in GC
Thermal Conductivity
Flame ionization
Electron captured
Another detectors
• Flame photometric detector• Thermionic detector• FT-IR (GC-FT-IR)• MS (GC-MS)
Quantitative applications
• Environmental analysis• Clinical analysis/forensic may include• Consumer goods• Petroleum industry
Analysis of Chlorinated Pesticides in Water