A perfume's signature can be used to determine if it is real or fake. The emissions of a plant can provide information on the health of the plant. An innovative approach has been developed by researchers at the JGU and the MPIC. There are two mirror- image forms of most natural chiral substances. Every plant and perfume has a unique hallmark. For the first time, the research team has been able to identify compounds in complex mixtures of gases in real time using their new approach.
The new technique can be used in agriculture and the chemical industry. This technique will allow us to better understand the chemistry of the atmosphere by decoding the signals in the air around us. The partners are applying for a patent.
Synthetic odors are different from naturally occurring odors.
Nature has a fundamental property called chyronality. Our hands are a sign of this. In the same way that a right hand can't fit in a left-handed glove, several biomolecules can be found in two mirror-image forms that are non-superimposable. The bio-chemical activity of these Molecules can be affected by this. Plants emit emissions that are unique. Both the D- and L-isomers are naturally present in these. The scent of conifers and pines is caused by the molecule pinene. The state of health of the plant is the most important factor in determining the relative ratios of the two enantiomers.
The same principle applies in the case of blends of natural and synthetic components. Depending on whether the ingredients come from natural sources or synthetic ones, the D- and L-isomers will have different amounts of chiral ingredients. Synthetic substances in fake/counterfeit perfumes can have a different signature than the originals.
The European Union funded the research.
As part of the EU-sponsored ULTRACHIRAL project, the researchers from Mainz have developed a polarimetric method. They were able to see the differences in the optical rotation of the Molecules. They put a sample of a scent in a chamber which was exposed to light. They used an optical polarimeter to measure the intensity of the light. The current state-of-the-art equipment is not as sensitive as the researchers have been able to achieve.
The new approach provides us with precise results, faster and at better sensitivities than traditional techniques, without the need for any calibration before each measurement run." For the first time, our technique has been combined with gas chromatography to separate individual components. The lead author of the paper that was recently published in Science Advances explained that it was possible to identify the different forms of the same gas. The authors propose a lot of new applications for their detection method.
Quality control of perfumes is a particularly complex process as it contains hundreds or even thousands of different compounds. The researchers compared four authentic high-quality commercial perfumes with their low-cost counterfeits to see how effective their technique was. The Mainz-based team was able to distinguish the high-quality original perfumes from their imitations by using a single rapid measurement.
Monitoring plant health and pests is a potential use.
It is possible that the technique is of interest to the field of agriculture. The team was able to show that the emissions of the plant suddenly changed when it was damaged. Plants that are subject to disease have similar signatures. In practice, these signatures can be used to continuously monitor crop plants to make sure they are free of insects, if there is a shortage of water, or if there is a health problem.
Further insights into the physical and chemical processes that occur in our atmosphere are possible thanks to the method. Many of the volatile organic compounds released into the environment are chiral. The chemistry and physics of the air around us can be affected by these molecule. Secondary organic aerosols can affect the Earth's solar radiation budget. We don't know the role chirality has in these processes. New instruments and new approaches are needed in order to understand this.
The portable version of the device will be developed in the future in order to make it easier to implement the new method.
More information: Lykourgos Bougas et al, Absolute optical chiral analysis using cavity-enhanced polarimetry, Science Advances (2022). DOI: 10.1126/sciadv.abm3749 Journal information: Science Advances
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