GC×GC–FID Analysis

How does GC×GC work?

GC×GC involves two columns: a primary column that is typically 20–30 m long, and a short secondary column that is 1–5 m long. The two columns are connected with a modulator. As in one-dimensional GC, the sample is introduced into a heated port and swept through the primary column by a carrier gas.

The peaks that elute are then sampled (ideally three or four times per peak) and each fraction is re-injected as a narrow chromatographic band into the secondary column. Passage through the secondary column is quick to ensure sharp peaks and no band overlap, with elution usually taking place in under 10 seconds. Following elution from the second column, detection takes place, and the signal is processed to generate a three-dimensional ‘surface plot’ (which can alternatively be viewed as a two-dimensional ‘contour plot’).

Importantly, the primary and secondary columns used in GC×GC have different stationary phases, allowing a mixture to be separated on the basis of two different properties – typically volatility (molecular weight) and polarity. These can be set up in one of two ways:

• Normal-phase GC×GC uses a non-polar primary column and a polar secondary column, and is the standard approach for most applications.
  
• Reverse-phase (or inverse-phase) GC×GC uses a polar primary column and a non-polar secondary column. This setup provides better separation of analyte groupings in certain cases.

Benefits of GC×GC

Compared to one-dimensional methods, GC×GC offers several benefits:

• Increased peak capacity, meaning better ability to analyse complex mixtures and detect ‘hidden’ components.
  
• More effective removal of background signals, meaning improved signal-to-noise ratios and better sensitivity.
  
• Simultaneous monitoring of multiple compound classes, meaning simplified sample preparation (and no need for prior fractionation).
  
• Structured elution of compound groups, meaning easier identification.

Just like one-dimensional methods, GC×GC is quantitative, highly reproducible, and compatible with a range of detectors, including FID and TOF MS.

Why choose INSIGHT-Flow GC×GC flow modulator?

• Cryogen-free operation lowers running costs for routine GC×GC.
  
• No volatility restrictions for confident analysis of VOCs (<C₅) and SVOCs
  
• Complete analyte transfer from 1D to 2D column
  
• Excellent repeatability for routine applications – rigid retention times and peak area RSDs typically <5%.
  
• Flexible configuration options, including GC×GC, heart-cut GC–GC, backflushing and parallel detection (e.g. TOF MS and FID).
  
• Retrofittable to all popular GCs.
  
• A compact design allows two INSIGHT devices to be configured in a single GC oven for enhanced productivity through dual-channel acquisition.
  
• Streamlined instrument control and data processing using the ChromSpace^® platform.
• Bleed line control kit accelerates the change between column configurations

SepSolve Analytical's INSIGHT flow modulator for GCxGC

Applications is GC×GC

GC×GC began as a highly specialised tool for researchers, but as the technology and software have been improved, and the user experience become more streamlined, applications have expanded.

Today, GC×GC is increasingly being used for many routine applications that can benefit from the technique’s ability to separate highly complex mixtures. These include:

• Petroleum analysis.
  
• Food and beverage analysis.
  
• Fragrance profiling.
  
• Biomarker discovery.
  
• Environmental monitoring.