1D GC-O/MS analysis

1D Flow Scheme

1D GC-O/MS is operated using LTM-GC Column 1. At the same time, carrier gas is supplied to the LTM-GC Column 2 by the PCM.

Heart-cutting

HeartCut Flow Scheme

User selected peaks eluted from LTM-GC Column 1 are transferred onto LTM-GC Column 2. The transferred peaks are focused at the head of the LTM-GC Column 2 with or without cryo-trapping depending on the compound volatility.

2D GC-O/MS analysis

2D Flow Scheme

After heart-cutting, the bulk of the sample can be effectively back flushed. A few minutes after the heart-cut, the temperature program for LTM-GC Column 2 is started.


 

Advanced Flavor and Fragrance Analysis

An extra GC dimension at your finger tips

Gas chromatography (GC) experts rely on sharp peaks and baseline resolution to provide accurate answers. To perform chromatographic analysis of real-world samples, analysts often must deal with either complex sample types such as essential oils and petroleum fractions, or complex matrices like biological fluids, foods, sludge, or polymers. Once the sample has been prepared for analysis, separation of all the individual compounds present by means of a single chromatographic separation can be challenging due to the compounds having different ranges of polarity, boiling point, solubility, MW, and concentration. It is therefore necessary to use innovative yet robust techniques that go beyond using a single chromatographic dimension to achieve compound separation. This sounds simple enough, but until now it hasn’t been, since techniques that require a second dimension (column) require a lot of additional hardware, including an extra GC. Not anymore: The patented GERSTEL Selectable 1D/2D-GC/MS System enables the best of both worlds. The system can be used for routine single dimensional GC/MS analysis, and with the click of a mouse, can be switched to perform twodimensional separation when needed for more complex matrices. This allows interesting sections of the chromatogram to be collected and concentrated from multiple runs to better separate and isolate trace compounds. This can, for example, be used for trouble shooting when off-odors are detected in a product. All this is performed using just one GC/MS system.
 

Food analysis is certainly not a trivial matter. The typical matrix is complex, often requiring several sample preparation steps and extensive sample cleanup. However, even well prepared samples can produce forests of overlapping peaks making it a case of not being able to see the trees for the forest. If a case of unresolved peaks is clearly at hand, or if an odor detected by using an Olfactory Detection Port (ODP) doesn’t match the peaks in the chromatogram, the user needs to have a good tool kit at her or his disposal. In this case, selectable multidimensional GC can be the technique that cuts through the thicket and provides clear, reliable answers whenever one-dimensional GC does not.

An attractive alternative to standard systems

Until now, multi-dimensional GC required the use of a dedicated system with two GCs coupled to each other. Due to the extra cost, and to the often limited utilization in the laboratory, such solutions didn’t always provide the best return on investment (ROI). GERSTEL now offers a solution that can be used for routine analysis as well as for special challenges. The patented GERSTEL Selectable 1D/2D-GC/MS is a flexible system, based on a single standard GC/MS instrument. It is both a routine analysis system and a complex problem solving system that offers heartcutting and two-dimensional separation on demand. Because of this dual functionality, when questions arise regarding a section of the standard one-dimensional chromatogram, this section in question can be transferred to a 2nd dimension, i.e. a GC column with different polarity to further increase separation.
Both columns are installed in the same GC and are heated independently using Low Thermal Mass (LTM) technology. The process of cutting a section of a chromatogram and introducing it to another column is called heart-cutting. The 1D/2D system can be used to determine analytes in either the 1st or the 2nd dimension in a flexible manner. Neither the GC run, nor analyte detection is interrupted during the run. Detection of the analytes that were transferred to the 2nd column follows using the same detector(s) used for the 1st dimension: MSD, Olfactory Detection Port (ODP), PFPD etc. etc.
Should lower detection limits be required for the analyte in question, the system enables heart-cutting from multiple repeat injection, with cryofocusing of the sections that were cut, on a GERSTEL Cryo Trap System (CTS). The accumulated sections are then transferred to the 2nd dimension once there is sufficient mass on column to perform the determination.

Wide Range of Applicability

Until now, Selectable 1D/2D-GC/MS systems have mainly been sold to, and used for food, flavor, and fragrance analysis, but any application that occasionally requires a 2nd dimension separation to solve a puzzle would benefit from having such a system available at a reasonable cost. Further, detection of analytes in both dimensions is performed using one or more detectors simultaneously including MSD, ODP, FID or PFPD. The complete system is efficiently and conveniently controlled by mouse-click through the GERSTEL MAESTRO software, integrated with the Agilent ChemStation. It couldn’t be simpler.


 

Application Example:
SBSE – 2D GC-O/MS analysis of odor-active compound in beer

 

1D GC-O/MS analysis
GC-O/MS can help locate the region of odor-active compounds within a complex Chromatogram, but insufficient resolution may still prevent reliable compound identification. A heart-cut of the region of interest followed by separation on a second column (second dimensional separation) provides the resolution needed to accurately identify individual compounds.

 

Heart-cutting and Backflushing
The system can be configured to perfom 2D GC-O/MS analysis without any hardware or column connection changes. After heart-cutting, the 1st dimensional column can be backflushed. An additional cryo-trap device is available if necessary.

 

Simultaneous MS and olfactory detection is possible in both 1D and 2D GC analysis modes.

 

2D GC-O/MS analysis

The peak of interest was well separated, and detected using olfactometry (ODP) on the second dimension. A well defined mass spectrum was obtained for the detected peak.

 
Library search

A Wiley library search tentatively identified the peak as a β-Damascenone.