Multi-Dimensional Gas Chromatography State-of-the-Art

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Multi-Dimensional Gas Chromatography
State-of-the-Art

• J.-M. D. Dimandja
• January 16, 2007

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Chromatography in Context
Selective Comprehensive
1D GC Sample Preparation Cartridges Conventional 1D GC
2D GC Heartcut GC-GC GCxGC
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GCxGC Instrumentation
Detector
Injector
Data Processor
Secondary Column
Primary Column
Modulator
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What is Modulation?
Demodulator
Modulator
Transmission
Desired Audio Signal
Audio Signal
AM FM
Demodulator
Modulator
Desired Multi-dimensional Signal
1st Dimension GC Signal
Transmission Through 2nd GC Dimension
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Role of the GCxGC Modulator

• Amplitude Modulation
• Frequency Modulation
• Phase Modulation
• The modulator plays a key role in the
  optimization of a GCxGC method

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Types of GCxGC Modulators

• Thermal Modulators
• Valve Modulators
• Will be covered by Prof. Seeley

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Modulator Figures-of-Merit

• Sampling efficiency
• Temperature operating range
• Technical sophistication
• Ruggedness
• Cost

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Evolution of Thermal Modulators

• Resistors
• Thermal scanners
• Thermal jets

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Thermal Resistor Principle

• Resistive heating
• Rapid cooling due to low thermal mass of the
  resistive film

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Rearview Defogger
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Defogger Operation

• Resistive paint heated
• Defogging occurs

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Napa Defogger kit
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The Original Resistor (Liu/Phillips, 1988)
Electrically Conductive Paint
Stationary Phase
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(No Transcript)
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Resistor Pros/Cons
Poor Good Excellent
Sampling Efficiency X
Temperature Range X
Technical Sophistication X
Ruggedness X
Cost X
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Improvements

• Two-stage modulation (Liu, 1989)
• Thicker stationary phase (Liu, 1990)
• Dry-ice resistor (Venkatramani, 1991)
• Stainless-steel, multi-stage resistor (Burger,
  2003)

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Resistor Summary

• Interfaced with HRMS (1994) and TOF MS (1996)
• Academia (prototype development), Industry
  (Shell), government RD (CDC)
• Cheap and easy to assemble, but not commercially
  viable

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Thermal Scanning Principle
Mechanically activated modulator that scans a
given section of the column to produce the
modulation.
1
2
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Dual-Oven Heat Shuttle (Xu, 1993)
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2
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Single-Oven Heat Shuttle (Xu, 1994)
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2
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Inside-Oven Cryo-Shuttle (Marriott, 1995)
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2
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Inside-Oven Heat Shuttle -- Thermal Sweeper
(Ledford/Phillips, 1997)
1
2
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Thermal Scanner Pros/Cons
Poor Good Excellent
Sampling Efficiency X
Temperature Range X
Technical Sophistication X
Ruggedness X
Cost X
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Thermal Scanner Summary

• First commercial system (Sweeper, 1997)
• Petroleum industry, government RD (CDC, CGA)
• Data processing issues (no software for automated
  visualization and/or quantitation)

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Jet Modulator Principle

• Active cooling and heating stages
• Thermal scanners only have one active stage
  (either heating or cooling, but not both)

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Single-Stage, Dual-Jet (Beens, 2001)
Trapping phase
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Single-Stage, Dual-Jet
Release phase
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Two-Stage, Quad-Jet Modulation (Ledford, 2001)
TRAP
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Two-Stage, Quad-Jet Modulation
FOCUS
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Two-Stage, Quad-Jet Modulation
RELEASE
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Two-Stage, Dual-Jet Modulation (Ledford, 2002)
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Two-Stage, Dual-Jet Modulation
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Two-Stage, Dual-Jet Modulation
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Two-Stage, Dual-Jet Modulation
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Thermal Jets Pros/Cons
Poor Good Excellent
Sampling Efficiency X
Temperature Range X
Technical Sophistication X
Ruggedness X
Cost X
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Thermal Jet Summary

• Curent commercially available state-of-the-art in
  GCxGC
• Industry, academia, government
• Achilles heel consumables
• Gaines/Frysinger solution
• Harynuk/Gorecki solution

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Conclusions
Instrument Development Modulation
Application Development Demodulation (Data Processing Software)