Gas Chromatography Compiled by : Imanuelle Orchidea

Definition A chromatographic technique in which the mobile phase is a gas Gas Liquid Solid Gas –Liquid/ Gas-Solid Chromatography

perekam Tabung gas Rangkaian penghubung & penguat

Mobile phase Inert gas ( He, Ar, N 2 ) Carry the sample Flow rates determined with a flow meter placed at a column outlet Column typeFlow rate Packed column mL/min Capillary column1-25 mL/min

Packed columns Capillary columns

Packed Columns – Glass/stainless steel/copper/aluminum – 2-6 m in length, internal Ø 2-4mm – Particle Ø ranging from µ m to µ m – 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 µ m, megabore up to 530 µ m Handle smaller samples ( < 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 – SiR 2 – O - (SiR 2 – O) n – SiR 3 HO – CH2 – CH2 – (O – CH2 – CH2)n – OH

STAT.PHASEPOLARITYTRADE NAME(T)LIMITAPPLICATIONS SqualaneNon-polarSqualane150Low boiling aliphatic hydrocarbons Apezion LNon-polarApezion L300Amides Fatty acid methyl esters High boiling aliphatic HC Terpenoids Polydimethyl siloxane SlightlySE Alkaloids* Amino acid derivatives ** Drugs # pesticides ## Phenols & steroids 50% methyl- 50%phenyl polysiloxane ModerateOV-17375*, #, ##, Polyaromatic hydrocarbons Polychlorinated biphenyls 50%TFP- 50%MPSO ModerateOV *,**, #, halogenated compounds, ketones, phenols 50% CYP-50% phe-me-PSO PolarOV Nitriles, pesticides, steroids PEGPolarCarbowax 20M 225Aldehydes, esters, ethers, phenols

Introduction of samples 1.All constituents must be volatile 2.Appropriate concentration 3.Must not degrade the separation Volatile analyte from Non volatile matrix: 1.Liquid-liquid extraction 2.Solid phase extraction  SPME 3.Headspace sampling 4.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

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