Introduction to Gas
Introduction to Gas
Chromatography
Chromatography
Written by Bette Kreuz Written by Bette Kreuz
Produced by Ruth Dusenbery Produced by Ruth Dusenbery University of Michigan-Dearborn University of Michigan-Dearborn
2000 2000
Introduction Introduction
Gas chromatography is an instrumentalGas chromatography is an instrumental method for the separation and
method for the separation and
identification of chemical compounds. identification of chemical compounds.
Slide 1a Slide 1a
A sample is A sample is
introduced into aintroduced into a heated injector,heated injector,heated injector,heated injector,
carried through a separating columncarried through a separating columnseparating columnseparating column byby an
an inert gas, andinert gas, andinert gas, andinert gas, and
detecteddetecteddetecteddetected as a series of peaks on aas a series of peaks on aas a series of peaks on aas a series of peaks on a recorder
recorder recorder
recorder when components leave thewhen components leave the column.
Slide 1 Slide 1
Slide 2a Slide 2a
The instrument used for our The instrument used for our
experiments, a Varian 3350 gas experiments, a Varian 3350 gas chromatograph, is shown here. chromatograph, is shown here.
Slide 2 Slide 2 Carrier gas/ Carrier gas/ Carrier gas/ Carrier gas/ Regulator Regulator Regulator Regulator Varian 3350 Gas Varian 3350 Gas Varian 3350 Gas Varian 3350 Gas Chromatograph Chromatograph Chromatograph Chromatograph
Computer Controls for Computer Controls for Computer Controls for
Computer Controls for
Method and Output Method and Output Method and Output
Slide 3a Slide 3a
Chromatographic separation involvesChromatographic separation involves the use of a
the use of a stationary phasestationary phasestationary phasestationary phase and aand a mobile phase
mobile phase mobile phase
mobile phase..
Components of a mixture carried inComponents of a mixture carried in the mobile phase are
the mobile phase are differentiallydifferentiallydifferentiallydifferentially attracted to the stationary phase attracted to the stationary phase attracted to the stationary phase
attracted to the stationary phase andand thus
thus move through the stationarymove through the stationarymove through the stationarymove through the stationary phase at different rates
phase at different rates phase at different rates
Slide 3 Slide 3 T=0 T=0 T=10’ T=10’ T=20’ T=20’ Injector Injector Injector
Injector DetectorDetectorDetectorDetector
Most Most Most
Most Interaction with Stationary PhaseInteraction with Stationary PhaseInteraction with Stationary PhaseInteraction with Stationary Phase LeastLeastLeastLeast Flow of Mobile Phase
Flow of Mobile Phase Flow of Mobile Phase
Slide 4a Slide 4a
In gas chromatography In gas chromatography
the mobile phasethe mobile phasemobile phasemobile phase is anis an inert carrierinert carrierinert carrierinert carrier gas
gas gas
gas andand
the stationary phasethe stationary phasestationary phasestationary phase is ais a solidsolidsolidsolid or aor a liquid coated on a solid
liquid coated on a solid liquid coated on a solid
liquid coated on a solid contained in acontained in a coiled column.
Slide 4 Slide 4
Slide 5a Slide 5a
Columns can be short, largeColumns can be short, large
diameter packed column or long, diameter packed column or long, very small diameter capillary
very small diameter capillary columns.
columns.
Each has its own use and associatedEach has its own use and associated advantages and disadvantages.
Slide 5 Slide 5
Slide 6a Slide 6a
The mobile phase or carrier gas The mobile phase or carrier gas
flows through the instrument from a flows through the instrument from a pressurized tank.
pressurized tank.
Flow rate is controlled by a two stageFlow rate is controlled by a two stage regulator on the gas tank and
regulator on the gas tank and additional controls within the additional controls within the instrument.
Slide 6 Slide 6 Two Stage Two Stage Two Stage Two Stage Tank Regulator Tank Regulator Tank Regulator Tank Regulator GC Flow Controller GC Flow Controller GC Flow Controller GC Flow Controller
Slide 7a Slide 7a
The column is contained in a heated The column is contained in a heated oven that is preceded by a heated oven that is preceded by a heated injector port and followed by a
injector port and followed by a
heated detector unit which produces heated detector unit which produces the output.
the output.
A set of preprogrammed parametersA set of preprogrammed parameters regulate the operation of the system. regulate the operation of the system.
Slide 7 Slide 7
Slide 8a Slide 8a
The injector, column oven and The injector, column oven and
detector components of the Varian detector components of the Varian 3350 gas chromatograph are shown 3350 gas chromatograph are shown here.
Slide 8 Slide 8
Injector Injector Injector
Injector DetectorDetectorDetectorDetector
Column in Oven Column in Oven Column in Oven
Slide 9a Slide 9a
Preprogrammed parameters, called aPreprogrammed parameters, called a separation
separation separation
separation methodmethodmethodmethod, control the, control the operation of the system.
Slide 9 Slide 9
Control Panel sets Separation Method Control Panel sets Separation Method Control Panel sets Separation Method
Slide 10a Slide 10a
Samples may be pure compounds.Samples may be pure compounds.
However, they are often prepared asHowever, they are often prepared as dilute solutions due to the sensitivity dilute solutions due to the sensitivity of the detection methods.
Slide 10 Slide 10 Dilute Dilute Solution Solution Pure Pure Sample Sample
Slide 11a Slide 11a
When the system is ready, asWhen the system is ready, as
indicated by the ready light, samples indicated by the ready light, samples are injected into the injector port
are injected into the injector port where they are vaporized and
where they are vaporized and
carried into the column by the carrier carried into the column by the carrier gas.
Slide 11 Slide 11 10 10 10 10 ll Syringe Syringe Syringe Syringe l l
Slide 12a Slide 12a
Separation of the components of theSeparation of the components of the mixture occurs in the column.
mixture occurs in the column.
Compounds differentially retained inCompounds differentially retained in the stationary phase reach the
the stationary phase reach the detector at different times to detector at different times to
produce a set of peaks along the produce a set of peaks along the time line.
Slide 12 Slide 12 Packed Column Packed Column Packed Column Packed Column installed in Oven installed in Oven installed in Oven installed in Oven Compartment. Compartment. Compartment. Compartment. Exit to Exit to Exit to Exit to Detector Detector Detector Detector Enter Enter Enter Enter from from from from Injector Injector Injector Injector
Slide 13a Slide 13a
The detector response is sent to a The detector response is sent to a
computer system where the progress computer system where the progress of the sample is monitored on the
of the sample is monitored on the computer monitor in graphical form computer monitor in graphical form that displays detector response as a that displays detector response as a function of run time.
Slide 13 Slide 13
Slide 14a Slide 14a
Each component of the mixtureEach component of the mixture
reaches the detector at a different reaches the detector at a different time and produces a signal at a
time and produces a signal at a characteristic time called a
characteristic time called a retentionretentionretentionretention time
time time
time..
The area under a peak The area under aarea under aarea under a peakpeakpeak is related tois related to the
the amount of that componentamount of that coamount of that coamount of that componentmponentmponent
present in the mixture. present in the mixture.
Slide 14 Slide 14
Slide 15a Slide 15a
The detector information can also sent The detector information can also sent to a printer that produces hard copy of to a printer that produces hard copy of the chromatographic run.
Slide 15 Slide 15
Slide 16a Slide 16a
In the printout of the chromatographic In the printout of the chromatographic analysis:
analysis: the
the number of peaksnumber of peaksnumber of peaksnumber of peaks correlates with thecorrelates with the number number number number of components of components of components
of components in the sample,in the sample, the
the area under each peakarea under each peakarea under each peakarea under each peak correlates withcorrelates with the
the
relative amount of that component relative amount of that component relative amount of that component
relative amount of that component in thein the sample,
Slide 16 Slide 16
