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Odour screening in action!
Odour is caused by volatile organic compounds, which we track through GC-Sniffing.
Introduction
Products and chemicals are widely used in many businesses. These often have a distinct odour, which can at times cause employees to question the safety of that product. How is it that you figure out which components underlie the perceived odour? And how about safety?
An odour was detected in this study, described as cocoa and toasted. After internal research, the company is able link the smell to a specific product. At NOLAB, the product was scrutinised through odour screening using GC-Sniffing, which both collects sensory information and detects volatile organic compounds (VOC).
In this way, we aim to find out which VOC are responsible for the typical odour observed. It is important to keep this description as objective as possible. This makes it possible, based on the odour, to identify certain groups of VOC that could be considered as the cause of this odour.
Preparation of samples
The product was supplied as a very fine powder with a light brown to reddish-brown colour. To capture the emission released by this product, dynamic headspace sampling was developed to capture the emissions released by the product,
involving the components emitted by the product being captured. To match this emission – which we create on a lab scale – with reality, the product was heated to the same temperature used during the production process.
Analysis via GC-Sniffing of the components released.
To identify the odour-relevant components, a GC-Sniffing (or GC-O) analysis was performed. In doing so, the device identifies the VOC, which could be brought into the device after sample preparation. In the specific setup for GC-Sniffing, the VOC are presented simultaneously to two detectors.
The first detector is responsible for VOC identification and quantification. The second detector is a sniffing port, where the "sniffer" (human nose) evaluates the components one by one for odour character and intensity.
Which component can be linked to which odour?
The odour – released by the product – is a composition of different odours, originating from different components. These can have reinforcing or weakening effects on each other. It is at times extremely clear which component causes a specific odour. Additional data such as odour threshold value, or literature data regarding odour description of components, can often confirm these results.
The challenge concerns perceived odours, to which no specific molecule can be linked. This often indicates very low odour threshold values, which are below the detection capabilities of even the most sophisticated equipment. Thus, during GC-Sniffing, the typical odour of the product was detected but no component could be linked to it.
All available information from the analyses and our expertise at NOLAB provide a targeted search. For example, pyrazines were evident in the product's emissions and appear to be present in the aroma of coffee. The fact that these pyrazines also have very low odour threshold values is consistent with our earlier suspicion. Here we have a component that is detectable in a very low concentration with the nose, but is not detected by the device. Its odour description, cocoa and toasted, is also clearly related to coffee.
A number of pyrazines were analysed via GC-Sniffing with the following astonishing results. One pyrazine had the same odour and was detected at the same time in the analysis as the main odour in the sample. Thus, this pyrazine is responsible for the perceived odour of the product. This was a tremendous relief, because such low concentrations are fortunately not harmful but are good indicators to manage the process.
Conclusion
Proper sample preparation is very important for determining the VOC responsible for the perceived odour. In addition, the human nose is still often the most sensitive detector for detecting odour. By using GC-Sniffing, the nose is also involved in the analysis.
With knowledge of this, targeted further searches can be made to identify VOC, even if these are difficult to measure.
Would you like to know which VOC determine the (deviating) odour of your product?
How can we help?
Do you have questions about VOC analysis? We can be reached via the channels below or leave a message on our contact page.