GCxGC: Theory, Practice and Optimizationand … Theory, Practice and Optimizationand Optimization...
Transcript of GCxGC: Theory, Practice and Optimizationand … Theory, Practice and Optimizationand Optimization...
GCxGC: Theory, Practice GCxGC: Theory, Practice and Optimizationand Optimizationand Optimizationand Optimization
Pete Stevens
Life Science & Chemical Analysis Centre
St. Joseph, Michigan, USA
Presentation OutlinePresentation Outline• An Introduction to GCxGC• An Introduction to GCxGC
– What is GCxGC?– GCxGC Hardware– Interpreting GCxGC Chromatograms
• Optimization of a GCxGC SeparationOptimization of a GCxGC Separation
• Applications– Advanced Data Processing
• Classifications• Scriptingp g
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What is GCxGC?What is GCxGC?Multi-Dimensional Gas ChromatographyMulti-Dimensional Gas Chromatography
– 2DGC vs. GCxGC• 2DGC
– Heart-Cutting– Heart-Cutting» Diverting a portion of effluent from a column onto a column of
a different stationary phase– Multiple Columns
» Splitting the effluent from a column onto multiple columns of differing stationary phases
GCxGC (Comprehensive Two dimensional Gas Chromatography)• GCxGC (Comprehensive Two-dimensional Gas Chromatography)– Comprehensive
» All material that enters the 1st dimension column passes through the 2nd dimension column to the same detectorg
– Uses a “Modulator” to partition 1st column effluent as discrete plugs onto the 2nd dimension column
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HeartHeart--cutting (2DGC)cutting (2DGC)
Detector “A”Stationary Phase “A”
Inlet Stationary Phase “A”
Detector “B”Stationary Phase “B”
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HeartHeart--cutting (2DGC)cutting (2DGC)
Detector “A”Stationary Phase “A”
Inlet Stationary Phase “A”
Detector “B”Stationary Phase “B”
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HeartHeart--cutting (2DGC)cutting (2DGC)
Detector “A”Stationary Phase “A”
Inlet Stationary Phase “A”
Detector “B”Stationary Phase “B”
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HeartHeart--cutting (2DGC)cutting (2DGC)
Detector “A”Stationary Phase “A”
Inlet Stationary Phase “A”
Detector “B”Stationary Phase “B”
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HeartHeart--cutting (2DGC)cutting (2DGC)
DetectorDetector
Detector “A”
Detector “B”
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HeartHeart--Cut 2DGCCut 2DGC
• Each column requires an independent detector
• Each Heart-Cut must be targeted at a specific coelution
• Two data files
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Capillary GC SchematicCapillary GC Schematic
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Thermally Modulated GCxGC SchematicThermally Modulated GCxGC Schematic
Column JunctionColumn Junction
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Simplified GCxGC FlowSimplified GCxGC Flow
DetectorModulatorInlet
1st Dimension Column 2nd Dimension Column
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ModulationModulationModulator has two functions in GCxGC:• Modulator has two functions in GCxGC:
1) Collect and focus segments of effluent from the primary columncolumn
2) Act as the injector for the secondary column
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
Cold Zone
Relatively Broad 1st Dimension Analyte Band
1st Dimension Column 2nd Dimension Column
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
1st Dimension Column 2nd Dimension Column
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
Hot Zone
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Focusing in the Thermal ModulatorFocusing in the Thermal Modulator
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Detector Requirements for GCxGCDetector Requirements for GCxGCQuantitation requires a minimum of 10 data points across aQuantitation requires a minimum of 10 data points across a
peak in order to define it
50 ms peak width at base
Need 10 data points / peak
5 ms between data points5 ms between data points
Minimum Required Sampling Rate:
50 ms
200 Hz 200 Hz for a 50 ms wide peak
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Volatility RangeVolatility RangeGood Peak Shape and Width over Wide Volatility RangeGood Peak Shape and Width over Wide Volatility Range
Maximum columntemperature toolow for fast elutionand a narrowpeak
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GCxGC HardwareGCxGC Hardware
Dual-Stage Quad-jet Thermal Modulator
• Utilizes LN2 or a Closed-loop Chiller for Cooling
• Utilizes an Secondary Oven for Independent Temperature Control of the Individual Columns
• Modulation Occurs on the Beginning of the 2nd Dimension Column• Modulation Occurs on the Beginning of the 2nd Dimension Column
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LECO’s DualLECO’s Dual--stage Quad Jet Thermal Modulatorstage Quad Jet Thermal Modulator
Stage 2
COLD JETSCOLD JETSHOT JETSHOT JETS
g
HOT JETSHOT JETS
Stage 1g
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LECO’s GCxGCLECO’s GCxGCPrimary Column
Secondary Oven
Primary Column
Secondary Oven
S d C lSecondary Column
Modulator
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCGC××GC: DualGC: Dual--stage Quadstage Quad--jet Thermal Modulationjet Thermal Modulation
1st Dimension Column 2nd Dimension Column
1 2
Hot Jets
1 2
1 2
Cold Jets
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GCxGCGCxGC OverviewOverview
• GCxGC is accomplished through a series of rapid, independent 2nd dimension separationsindependent 2 dimension separations
• The modulator serves two functions: focusing sections of g1st dimension column effluent and acting as the injector for the 2nd dimension column
• GCxGC is comprehensive. All material that enters the 1st
column passes through the modulator, the 2nd column and p g ,on to the detector
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GCxGC OverviewGCxGC Overview
• Primary column separates components based on volatility and also generates wide bandswide bands
• The modulator focuses and re-injects time-fractions of the primary column effluent onto the second column for a second separation
– 5+ modulations per peak
• The second column performs a rapid p pseparation of each injected sample from the modulator based on polarity
– tm ~ 1.0 s for a 1.0m column
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The GCxGC ProcessThe GCxGC Process
ModulatorInletThe signal as seen by the detector
0 25 I D
Detector
0.25 mm I.D.0.10 mm I.D.
PrimaryColumn
SecondaryColumn
Th ffl t f th i l i f d d t d b th d l t i t di t
2nd
Col
umn
Sep
arat
ion
The effluent from the primary column is focused and segmented by the modulator into a discrete“plug”. Each plug is then injected onto the secondary column by the modulator, where it isseparated. The GCxGC process is a series of independent second column separations.
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Retention PlaneRetention PlaneTi
me
Ret
entio
n T
men
sion
R2n
dD
im
1st Dimension Retention Time
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Contour PlotContour Plot
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Contour PlotContour Plot
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Surface PlotSurface Plot
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Features of a GCxGC Contour PlotFeatures of a GCxGC Contour PlotAlkyl-sub PhenanthrenesGCxGC of Raw Diesel
Mor
e Alkyl sub Phenanthrenes
C
GCxGC of Raw Dieselity
Alkyl-sub Napthalenes
C1
C2
Pola
ri(W
ax)
Alkyl-sub Benzenes
C1C2
C3 C4
C1 C2 C3
n-Alkanes
Boiling PointLower Higher
(5% diphenyl)
Less
1
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Optimizing a GCxGC SeparationOptimizing a GCxGC Separationgg
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What is an “Orthogonal” Separation?What is an “Orthogonal” Separation?
A separation scheme is orthoganal when twoseparations are performed by mechanisms that arei d d t f thindependent from one another
Example: SDS PAGE → LC
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What is an “Orthogonal” Separation?What is an “Orthogonal” Separation?In GCxGC an orthoganal separation occurs when theIn GCxGC, an orthoganal separation occurs when theseparation mechanisms of the two columns are independentfrom one another
olar
ityP
Boiling Point
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In GCxGC, the orthogonality of the column set determineshow efficiently the available chromatographic “real estate” iny g pthe retention plane is used.
eR
eten
tion
Tim
e2n
dD
imen
sion
R
1st Dimension Retention Time
2
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ORTHOGANAL SEPARATION
Retention PlaneRetention PlaneTi
me
Ret
entio
n T
men
sion
R2n
dD
im
1st Dimension Retention Time
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Advantages of GCxGCAdvantages of GCxGCPeak CapacityPeak Capacity
( ) ( ) 122/112/1
−⎟⎟⎠
⎞⎜⎜⎝
⎛+Δ
=WW
tSN r ( )∑ +=j
it SNSN 1 = 85 peakswhere
⎤⎡tN⎞⎛ Δ t⎥⎦
⎤⎢⎣
⎡+=
m
lastr
s tt
RNCp )(ln
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( ) ( ) 122/112/1
−⎟⎟⎠
⎞⎜⎜⎝
⎛+Δ
=WW
tSN rX = 2550 peaks
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Increased Peak Capacity in GCxGCIncreased Peak Capacity in GCxGC
men
sionTheoretical Maximum Peak Capacity
of 2
ndD
imPeak Capacity of 1st Dimension
X
Cap
acity
o
Peak Capacity of 2nd Dimension
Pea
k Peak Capacity of 1st Dimension
Actual Maximum Peak Capacity is Lower
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Advantages of Thermally Modulated GCxGCAdvantages of Thermally Modulated GCxGC
• Increased detectability resulting from focusing in the modulator
• Increased chromatographic resolution
• Increased peak capacity
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Parameters Commonly Used In OptimizationParameters Commonly Used In Optimization
• Temperature Program• Temperature Program– Rate of temperature increase for columns
• Column Offset– Temperature difference between 1st dimension column and 2nd
dimension columndimension column
• Modulator Offset – Temperature difference between 2nd dimension column and
modulator hot jets
• Modulation Period– Dwell time of modulation cycle
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Temperature ProgramTemperature Program
• Increasing the rate of the temperature program will causethe analytes retention time on the primary column tothe analytes retention time on the primary column todecrease.
• GCxGC uses lower temperature program rates so that• GCxGC uses lower temperature program rates so thateach individual second dimension separation occurs under“isothermal” conditions. Having each second dimensionseparation occur under locally isothermal conditions helpsseparation occur under locally isothermal conditions helpsmaintain separation scheme orthoganality. Thisnecessitates that the use of longer modulation periodsrequires lower temperature ramps.
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Increased Temperature Program RateIncreased Temperature Program Rateim
eet
entio
n Ti
men
sion
Re
2nd
Dim
1st Dimension Retention Time
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Oven Temperature OffsetOven Temperature Offset
• Increasing the temperature offset between the first and d di i l ill d t ti tisecond dimension columns will decrease retention times
in the second dimension.
• Decreasing the temperature offset between the first and second dimension columns will increase retention times i th d di iin the second dimension.
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Increasing Temperature OffsetIncreasing Temperature OffsetTi
me
Ret
entio
n T
men
sion
R2n
dD
im
1st Dimension Retention Time
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Decreasing Temperature OffsetDecreasing Temperature Offset
me
eten
tion
Tien
sion
Re
2nd
Dim
1st Dimension Retention Time
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Wrap AroundWrap Around
me
eten
tion
Tien
sion
Re
2nd
Dim
1st Dimension Retention Time
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GCxGC “WrapGCxGC “Wrap--Around”Around”
A B C
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GCxGC “WrapGCxGC “Wrap--Around”Around”
A1 B1 C1
A2 A3B2 B3
B4C2 C3
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Modulator OffsetModulator Offset
• The modulator offset describes the difference intemperature between the modulator block (hot jets) andtemperature between the modulator block (hot jets) andthe 2nd dimension oven. Modulator offset relates to theinjector function of the modulator. LECO recommends amodulator offset of at least +15 °C relative to themodulator offset of at least +15 C, relative to thesecondary oven temperature.
• The modulator offset would be increased to assist indesorbing high boilers.
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Temperature Offsets and ProgrammingTemperature Offsets and Programming
C l M TCol2 Max Temp
°C)
empe
ratu
re (°
Modulator Offset
ColMod
15 °C
Te
Col1
Col2 15 °C
Time
Column Offset
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Modulation PeriodModulation Period• Increasing modulation period allows for the prevention of
the wrap-around of compounds strongly retained on the2nd dimension. It would also, however, decrease thenumber of slices taken of the 1st dimension peak andincrease the likelihood of overloading the modulator.
• Decreasing the period would increase the number of 1st
dimension slices, but would also increase the likelihoodof wrap-around in the 2nd dimension and decrease theamount of separation obtained on the 2nd dimensioncolumn.
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Increasing Modulation PeriodIncreasing Modulation Periodio
n Ti
me
on R
eten
td
Dim
ensi
o
1st Dimension Retention Time
2nd
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Decreasing Decreasing ModulationModulation PeriodPeriod T
ime
Ret
entio
nim
ensi
on
2nd
D
1st Dimension Retention Time
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Resolution on the xResolution on the x--AxisAxisTi
me
Ret
entio
n m
ensi
on R
6 sec6 sec 6 sec6 sec6 sec 4 sec 4 sec 4 sec4 sec4 sec
2nd
Di
1st Dimension Retention Time
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Modulation PeriodModulation Period
• The resolution on the x-axis is equal to the modulation period.p
• Compounds that are separated by less than the d l ti i d bi d i th d l tmodulation period are recombined in the modulator.
• A good rule of thumb is that the modulation period should• A good rule of thumb is that the modulation period should be as short as possible while obtaining the necessary separation in the 2nd dimension.
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GCxGC ApplicationsGCxGC Applications
Environmental
MetabolomicsMetabolomics
Petroleum
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EnvironmentalEnvironmental
GCxGCGCxGC--TOFMS AnalysisTOFMS Analysisyyofof
PDBE’s and PCB’s in FishPDBE’s and PCB’s in Fish
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fish
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fish
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fish
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fish
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fishtribromodiphenyl ether 5 8 11 14 eicosatetraynoic acidtribromodiphenyl ether 5,8,11,14-eicosatetraynoic acid
dehydroabietic acid methyl ester
3-(4-Methoxyphenyl)-2-propenoic acid 2-ethylhexyl ester
5-heptyldihydro- 2(3H)-furanone
3-(4-Methoxyphenyl)-2-propenoic acid 2-ethylhexyl ester
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Environmental Environmental –– PBDEs & PCBs in FishPBDEs & PCBs in Fish
tribromodiphenyl ether5,8,11,14-eicosatetraynoic acid
dehydroabietic acid methyl ester
5-heptyldihydro- 2(3H)-furanone
3-(4-Methoxyphenyl)-2-propenoic acid 2-ethylhexyl ester
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MetabolomicsMetabolomics
GCxGCGCxGC--TOFMS AnalysisTOFMS AnalysisGCxGCGCxGC--TOFMS AnalysisTOFMS Analysisofof
SulfurSulfur--containing Metabolites ofcontaining Metabolites ofSulfurSulfur--containing Metabolites of containing Metabolites of Asparagus in UrineAsparagus in Urine
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Pre-Asparagus Consumption
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Post-Asparagus Consumption
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Post-Asparagus Consumption
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PetroleumPetroleum
GCxGCGCxGC--TOFMS AnalysisTOFMS Analysisyyofof
DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
~ 3280 Peaks w/ S/N ≥ 100
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDieselPeak # Name R.T. (s) Classifications UniqueMass S/N Height Area
56 Cyclohexane, 1,1,3-trimethyl- 571.5 , 0.710 Alkanes 69 1301.2 5008.6 26512
57 Cyclohexane, 1-ethyl-2-methyl-, cis- 582.5 , 0.700 Alkanes 55 370.8 2231 11696
58 4-Nonene 593.5 , 0.710 Alkanes 55 183.66 799.83 4643.7
59 Cyclohexane, 1,1,2-trimethyl- 599 , 0.720 Alkanes; Alkenes 55 482.25 2672.9 17540
60 Ethylbenzene 599 , 1.210 C2 Benzenes 91 4394.5 21330 156411
61 Thiophene, 2-ethyl- 599 , 1.400 97 285.33 912.7 7362.1
62 Cyclohexane, 1,1,2-trimethyl- 610 , 0.720 Alkanes; Alkenes 69 194.63 1054.1 7455.4
63 1,2,4,4-Tetramethylcyclopentene 615.5 , 0.770 Alkenes 109 464.77 1275.4 7781
64 Benzene, 1,3-dimethyl- 615.5 , 1.240 C2 Benzenes 106 9223.3 28095 215876
65 Thiophene, 2,5-dimethyl- 615.5 , 1.310 C2 Benzenes 111 153.51 419.06 3456.2
66 Heptane, 3,4-dimethyl- 621 , 0.690 Alkanes 43 157.94 1419.1 8813.9
67 Cyclopentane, 1-methyl-3-(1-methylethyl)- 626.5 , 0.720 Alkanes; Alkenes 55 229.4 2143.6 15653
68 Pentalene, octahydro- 626.5 , 0.810 Alkenes 67 407.51 1439.7 12688
69 Thiophene, 2,4-dimethyl- 626.5 , 1.430 111 332.29 907.17 7555.6
70 2,4-Heptadienal, (E,E)- 632 , 0.830 81 118.5 402.54 3241.6
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Petroleum Petroleum -- DieselDiesel
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Petroleum Petroleum -- DieselDiesel
Base Peak = m/z 91, 105 or 119
And
Rank(2) = m/z 134
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Petroleum Petroleum -- DieselDiesel
1-methyl-3-(1-methylethyl)-benzene
1,2,3,5-tetramethyl-benzene
4-ethyl-1,2-dimethyl-benzene
1-methyl-3-(1-methylethyl)-benzene
1-methyl-4-propyl-benzene
1-methyl-3-propyl-benzene
1 methyl 3 (1 methylethyl) benzene
1 methyl 3 propyl benzene
2-ethyl-1,4-dimethyl-benzene
1-ethyl-2,3-dimethyl-benzene
1-methyl-2-(1-methylethyl)-benzene
1-ethyl-2,4-dimethyl-benzene
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ConclusionConclusion• GCxGC is a versatile technique that is well suited to the• GCxGC is a versatile technique that is well-suited to the
analysis of complex mixtures
• GCxGC provides benefits over a conventional 1DGC separation including:
I d D t t bilit• Increased Detectability• Increased Chromatographic Resolution• Increased Peak Capacity
• LECO’s ChromaTOF software offers advanced data processing, such as Classifications and Scripting, which g gtake advantage of the structured nature of GCxGC data
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For More InformationFor More Information
Contact LECO at:
Life Science & Chemical Analysis CentreTelephone: 269-985-5714Telephone: 269 985 5714
Email: [email protected]@www.leco.com
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