On-line sampling of fragranced products
Discontinuous and continuous on-line sampling
On-line sampling, whether discontinuous (stepwise) or continuous, allows the monitoring of changes in fragrance profile with time – for example, to determine how a fragrance decays following release into the air – as well as making it easier to focus on key aroma components, for meaningful quality control.
What Markes offers
Markes’ systems allow both discontinuous and continuous on-line sampling, as described below.
Discontinuous on-line monitoring
The most versatile option for on-line sampling is the U-INLET, Markes’ direct inlet accessory, which pulls a fixed flow of air through a sample chamber and delivers the headspace directly into the focusing trap of the UNITY thermal desorber.
It can also be used to provide a carrier gas purge of sealed sample vessels, and for pulling a fixed flow of air through open sample chambers – for example vessels containing living organisms.
Use of the U-INLET allows large volumes of vapour to be sampled, greatly enhancing sensitivity relative to conventional equilibrium (static) headspace. It also allows characterisation of analytes over a wider volatility range, because the dynamic extraction of vapours prevents the bias towards more volatile compounds. Selective elimination of unwanted, high concentration interferences such as water or ethanol is also possible.
An alternative solution for discontinuous on-line sampling is the Air Server accessory for the UNITY thermal desorber, which provides automation for up to eight channels.
Continuous on-line monitoring
Markes’ TT24-7 thermal desorber uses twin-trap technology to continuously sample odour compounds over a wide boiling range with 100% sample collection efficiency. When used in conjunction with rapid or real-time analytical methods (such as fast GC), near-real-time monitoring can be achieved, allowing the analyst to identify even relatively minor changes in odour profiles as they occur. This can be useful, for example, to monitor the decay in the odour profile of a fragrance released into a room.
- For an example of near-real-time profiling of fragrance components from an air freshener using Markes’ TT24-7 thermal desorber, see Application Note 105.
- For more examples of the use of TD-based methods for the analysis of fragrance profiles of consumer products, see Application Note 052, or contact us to request a copy of our TD Applications Guide on food, flavour, fragrance and odour profiling.