Gas chromatography is an established analytical separation technique. It applies to the analysis of organic compounds. The GC is the instrument that makes it possible. It consist of an oven, a column, an injector, eventually an autosampler, a detector and a pneumatic system. The compounds are injected onto a column, vaporized, and separated according to their polarity and/or boiling point depending on the column chosen.

Olfactometry is the measurement of odors, good or bad. Olfactometers are commonly used in food, flavor and fragrance companies. These instruments are used mostly for consumer evaluation. GC-Olafctometry adds a dimension to the technique.

When they are separated prior to the olfactometry, the compounds responsible for an odor can be smelled one by one, and the odor broken down into multiple odors.
The instrument used for the olfactometry part is usually called a sniffer port.

Identification of odor, or compound responsible for an odor is one of the main applications of GC-O. This applies, for example, to the identification of the compound(s) responsible for the odor emitted by a flower. It can also be used for deformulation of products or, in a less pleasant application, the identification of the compound(s) responsible for an odor contamination in a product.

Identification of compounds is fairly easy using the spectroscopy technique available today. Knowing which one is responsible for the odor is a different story. Moreover, the human nose is often more sensitive than the detector available (MS, FID, PID, etc...). Therefore, an analysis of a product by GC/MS might not be enough to identify the odorous compounds.
This is where the human nose comes into play. By comparing the response from the detector (FID, MS, ...) to the response of the panelist (person who performs the GC-O) , it is easy to find out which compounds smell, which ones don't and what they smell like.

Quantitation of odor is a bit more challenging and requires preparation and training. It is not as exact as the quantitation done by straight GC or GC/MS, but gives a good idea of the quantity of compound used. It can, however, be combined with the results (if any) from the detector. As with a GC or GC/MS the panelist must be trained to recognize the odor intensity at different concentrations.

Important: The most important issue with GC-O is safety. Although the quantity of compound is small, smelling dangerous compounds can be hazardous. GC-O should not be conducted on unknown sample. A profile of the main components must be acquired and studied before running a sample by GC-O. If any harmful compounds are found, it is still possible to conduct GC-O, but alarms must be set to warn the panelist of the elution of such compounds.
Injection techniques such as headspace can be used to avoid injecting too many harmful compounds. Headspace injection is usually a valuable tool for GC-O and odor studies, as most of the compounds work well with this technique.

More info: view "download brochure" at page bottom.

The instrumentation for GC-O

No cold spot gives the possibility to sniff the high boiling compounds.
Transfer line is hot till the end
Maximum 300°C on the transfer line.
Protects your nose from drying by adding moist air to sniffing port.
Easy to connect the capillary column to the splitter.
Sitting down or standing up while sniffing.
Compact and easy to install on any GC instrument.
SplitManager software standard supplied.
Voice recording with replay function and voice recognition. (option

The PHASER is standard supplied with all capillaries, 4 port microchannel connector, nuts and ferrules and SplitManager software in order to make the installation. Only a GC mounting plate kit is needed.

Inside the GC-O system

The sniffer is standard supplied with the SplitManager software and a set of capillaries. With the SplitManager the installation of the sniffer becomes really easy.

A 4 port Silflow (SGE) microchannel device is used to ensure a reliable split flow between the GC detector and the nose cone.

Olfactory Voice recognition software

Phaser Software
Standard with all PHASERS a calculation program (splitManager) is supplied to make the correct capillary tubing´s in order to have a good split ratio between the nose and detector. The Olfactory Voicegram is an option and is not supplied with all units.

Analogue signals can be used direct and can be displayed live during the GC run. Data from a mass spectrometer can be imported after the GCMS analysis.