Fragrance : from the smell to the spectrometer

Fragrance : from the smell to the spectrometerFederico Collura Robin KämpfDylan KäserNovember 24, 2020

Analytical strategy course

Table of contents

1. Olfactive detection

2. Sensory panels

3. Electronic noses

4. Conventional analytical methods

5. Developed fragrance technologies

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How is an odour detected

• Flavors are detected at the olfactory bulb.

• Odour directly reach the receptors and tastes pass through the pharynx to get detected. Therefore we speak respectively of olfaction and retro-olfaction.

• It was shown that human olfaction is not necessarily worse than animals but differently specified (less olfactive communication e.g.).

• Different capacities can be developped such as detection, differenciation and quantification


© Discover magazine

Animal for compound detection


Olfactometry

• Sensory panels are very common in the perfume industry with trained professionals : the noses.

• The panel can do descriptive analysis to characterize their perception or discriminative analysis between samples.

• Their capacities can be combined with other methods to develop new aroma for instance.

• The main problem related to the panels is the subjectivity. People may have different sensitivity due to receptors for example but also different references in their background.


© Osmotech

Electronic noses

• Analytical instruments to get rid of the subjectivity

• Accurate composition detection and potential quantification with chemoelectric sensors (MOS, MOSFET, conductive polymers, etc.)

• Lack of sensitivity and need of targeted sensors are the main problem (each brand should have one to detect characteristic substances)

• Cost of large array to cover a bigger diversity of properties

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Yan, Y., et al. Chemoelectronic circuits based on metal nanoparticles. Nature Nanotech 11, 603-608 (2016)

Importance of the olfactory sense

• Warning sense− Rotten food− Tetrahydrothiophene

• Influence of other senses like tactile perception


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CORTEZ‐PEREIRA, C.S., BABY, A.R., KANEKO, T.M. and VELASCO, M.V.R. (2009), SENSORY APPROACH TO MEASURE FRAGRANCE INTENSITY ON THE SKIN. Journal of Sensory Studies, 24: 871-901. https://doi.org/10.1111/j.1745-459X.2009.00242.x

https://doi.org/10.1111/j.1745-459X.2009.00242.x

Why is it difficult to analyze scents?


• Photodetectors, microphones and tactile sensors are widely established

• No device yet which mimics the nose consisting of 300-400 olfactory receptors

Pelosi, P.; Zhu, J.; Knoll, W. From Gas Sensors to Biomimetic Artificial Noses. Chemosensors 2018, 6, 32.

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Understand what we‘d like to analyze – Perfume composition

• Fine perfume has more than 100 compounds

• Huge range of concentrations

• All kinds of functional groups

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• Essential oils

• Carrier oils

• Solvents

• Fixatives

• Modifiers/emulsifiers

• Dyes

• Antioxidants

Abedi, G.; Talebpour, Z.; Jamechenarboo, F. The Survey of Analytical Methods for Sample Preparation and Analysis of Fragrances in Cosmetics and Personal Care Products. TrAC Trends in Analytical Chemistry 2018, 102, 41–59. https://doi.org/10.1016/j.trac.2018.01.006.


https://doi.org/10.1016/j.trac.2018.01.006

GC/MS – The gold standard

• Advantages:− Able to resolve complex matrix− Great sensitivity− Quantification possible

• Disadvantages:− High analysis time (long columns needed)− Only for heat resistant and volatile compounds

• Often coupled with olfactometry port (GC-O-MS)

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van Asten, A. The Importance of GC and GC-MS in Perfume Analysis. TrAC Trends in Analytical Chemistry 2002, 21 (9), 698–708. https://doi.org/10.1016/S0165-9936(02)00807-5.

https://doi.org/10.1016/S0165-9936(02)00807-5

Extractive ESI - MS

• Advantages:− No sample preparation (probably dilution)− Fast analysis

• Disadvantages:− Memory effect of «sticky» compounds limits

sample throughput

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1. Chingin, K., Gamez, G., Chen, H., Zhu, L. and Zenobi, R. (2008), Rapid classification ofperfumes by extractive electrospray ionization mass spectrometry (EESI‐MS). Rapid Commun. Mass Spectrom., 22: 2009-2014. https://doi.org/10.1002/rcm.3584

MS

N2

ESI probe

perfume


https://doi.org/10.1002/rcm.3584

Paper Spray Mass Spectrometry

• Advantages:− Easy setup− No sample preparation− Very high throughput

• Disadvantages:− Results are not very producible− Not suitable for full analysis

• Good method to analyze the fingerprint of a perfume

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1. J. A. R. Teodoro,a H. V. Pereira,a D. N. Correia,b M. M. Sena,a E. Piccina and R. Augusti, Anal. Methods, 2017,9, 4979-4987


Paper Spray MS – An example


Ion Mobility Spectrometry

• Advantages:− Smaller and lighter than MS (mobility)− No sample preparation− Very good sensitivtiy

• Disadvantages:− Quantification not straightforward− Compound analysis difficult

• Working principle:− Separation by collision with gas molecules


Jared M. Clark, Keith A. Daum & John H. Kalivas (2003) Demonstrated Potential of Ion Mobility Spectrometry for Detection of Adulterated Perfumes and Plant Speciation, Analytical Letters, 36:1, 215-244, DOI: 10.1081/AL-120017274.

https://doi.org/10.1081/AL-120017274

Fragrance Technologies

• Encapsulation• Malodor Trapping• Pro-Perfumes


Herrmann, A. (Ed.). (2011). The chemistry and biology of volatiles. John Wiley & Sons.

https://cen.acs.org/articles/96/i5/encapsulation-taking-root-laundry-room.html

EncapsulationThis method is used for improving the performance of a fragrance. It can be a solution for several problems:• Decrease the evaporation rate of the fragrance,

control the release rate and provide sustained release;

• Reduction of reactivity;• Improve the compatibility with other constituents;• Stabilise and protect the fragrance during storage,

extending shelf life;• Increase deposition and adhesion.


http://www.encapsys.com/images-ads/capsules-on-human-hairBerger, R. G. (Ed.). (2007). Flavours and fragrances: chemistry, bioprocessing and sustainability. Springer Science & Business Media.

Materials used for Encapsulation• Polysaccharides and sugars (gums, starches, celluloses,

cyclodextrin, dextrose, etc.)• Proteins (gelatin, casein, soy protein, etc.)• Lipids (waxes, paraffin, oils, fats, etc.)• Inorganics (silicates, clays, calcium sulphate, etc)• Synthetics (acrylic polymers, poly(vinylpyrrolidone), etc.)


Chitosan

Hyaluronic Acidhttps://www.sciencedirect.com/science/article/abs/pii/S0927775718312391

Berger, R. G. (Ed.). (2007). Flavours and fragrances: chemistry, bioprocessing and sustainability. Springer Science & Business Media.

Methods of EncapsulationSpray-drying:• One of the most used processes;• Solvent-based method;• Compatible with heat-sensitive materials;• Good keeping quality of microcapsules;• Excellent redispersability of particles in

aqueous media.

Disadvantages:• Loss of very low boiling actives • Oxidation of some compounds


Malodour trappingA common characteristic of many offensive smells is the presence of –NH2, –SH, and C=C groups. Several methods to counteract foul-smelling compounds over time:• Aldehydes and esters as key components in

fragrances.• Mixture of two aldehydes, one of which having a

double bond in the alpha position, R–C=C–CHO.• Development of non-odorous materials that could

complex with the malodor molecules.• Zinc and copper salts.


Citral Cinnamic Aldehyde

Zinc Ricinoleate

Metazene

Rowe, D. (Ed.). (2009). Chemistry and technology of flavours and fragrances. John Wiley & Sons.

FebreezeComposition:A. From about 0.01% to about 1%, by weight of

the composition, of perfume wherein the perfume prefer ably comprises ingredients having a Clog P of 3 or Smaller;

B. From about 0.1% to about 5%. by weight of the composition of, water-soluble cyclodextrins;

C. From about 0.1% to about 10%, by weight of the composition, of water-soluble metallic salts;

D. From about 0% to about 3%, by weight of the composition, of solubilizing aid;

E. Aqueous carrier


Crini G., Fourmentin S., Fenyvesi É., Torri G., Fourmentin M., Morin-Crini N. (2018) Fundamentals and Applications of Cyclodextrins.

Trinh, Toan, et al. "Composition for reducing malodor impression on inanimate surfaces." U.S. Patent No. 5,783,544. 21 Jul. 1998.

Pro-Fragrances and Pro-PerfumesTypical triggers:• Temperature;• Exposure to Light; • Water;• Oxygen;• Enzymes from Different

Microorganisms or Bacteria;


Herrmann, A. (Ed.). (2011). The chemistry and biology of volatiles. John Wiley & Sons.

How can we evaluate the effectiveness of these technologies?Head-Space Gas Chromatography coupled with Solid Phase Micro Extraction (HS-SPME-GC):Advantages:• Portability• Automation• Sensitivity• No interference with the sampleLimitations:• Enhancement of selective compounds


Dupes in the fragrance industry

• In 2013 the French justice declared that the fragrances cannot be protected itself. However the copy of a brand and its image can lead to condemnation.

• Aside the natural extracts justifying the price, the know-how and the quality of the product such as its stability can make the difference between a dupe and an original

• Particular synthetic compounds could be patented similarly to drugs and even if they only contribute to the product stability or other property

• Analytics can be used to imitate a perfume but could be non-profitable due to the measurement costs


© goodtoknow.co.uk

Analysis of raw compounds

• Determination between natural, animal and synthetic sources− Oils from natural plant extracts are multicompound mixtures

− Animal scent sources:− Musk / Muscone (today almost exclusively synthetic)− Ambergris / Ambroxide (still in use, but very expensive)− Civet / Civetone


Conclusion

• We wish you a joyful and fragrant Advent season

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• Development towards electronic noses is an active field of research

• Perfume forgery is wide spread

• There are a lot of different analytical methods and approaches to counterfeit forgery

Thank you for your attention !


Fragrance : from the smell to the spectrometer

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