Fragrances

1. Fragrances Johanna Scoul Martina Lippe 07.10.2014

2. Case Study • At the beginning of the distillation of menthone made from natural menthol there is a „green/mossy“ note. • The off-note is in the first distillation fraction -> lower boiling point than menthone • Menthone made from artificial menthol does not have this issue. • With a GC-MS analysis there is no peak visible which could explain the smell.

3. Whatisthe off-note? • 1.) The off-note is a totally different species than menthone • Very low concentration and is therefore not detected • 2.) The off-note is an isomer of menthone • 4 Stereoisomers • Menthones: minty odor • Isomenthones: slightly musty odor • Diastereomers can be excluded as they should be separable by GC • Enantiomer: make a chiral GC • -> Case 1.) H. Surburg; J. Panten,CommonFragranceandFlavor Materials: Preparation, Properties andUses, 5thedition, Wiley, 2006, p. 63.

4. Analytical strategies • Get the off-note in good purity • Preparative gas chromatography • Purificationmethod • Spinning-band distillation • Differencein boilingpoint

5. Preparative GC • Separate componentsformoreadvanceduse • Requires a columnwith a larger diameter • A detectorisneeded • FID (Flame IonizationDetector) -> forcarbon • ECD (Electron Capture Detector) -> forhalogenatedcompounds • NPD (Nitrogen PhosphorusDetector) -> fornitrogenandphosphorus • Human nose -> GC sniffingtechnique

6. GC sniffingtechnique • Splitter attheoutletofthe GC column • Detector • Sniffingdevice • -> gettheretention time ofthe off-note http://sim-gmbh.de/en/gcms/sim-olfactory-detector.html http://resources.schoolscience.co.uk/ICI/16plus/smells/smellsch3pg2.html

7. GC/MS-detection • GC • Mostly apolar stationary phase • Separates according to boiling point -> possible to limit the mass range of the off-note • MS • Mostly quadrupole • High mass flow rates possible • Integration time for one mass is very short • For better sensitivity the mass range should be limited • -> Selected ion monitoring • Normally: 10-10 g, can be improved by a factor of 100 • -> maybe possible to see the off-note in the spectrum

8. Further Suggestions • Different Ionisation Method (normally: electron impact) • Chemical ionisation with negative ions • Different mass spectrometer • FT-ICR • GC-GC • Two columns • Interface that samples or collects the effluent from the first column and introducing it to the second column • Two separation mechanisms or temperatures • -> Separation is highly selective http://www.pg.gda.pl/chem/CEEAM/Dokumenty/CEEAM_ksiazka/Chapters/chapter6.pdf

9. Spinning-band distillation • Fractionatingcolumnsimprovestheseparationbyhelpingthemixedvapoursto cool, condenseandvaporizeagain (Raoult‘slaw) • Spinning-band distillation: useof a helical, rotating band (teflonormetal) http://en.wikipedia.org/wiki/Fractionating_column http://www.brinstruments.com/fractional-distillation/spinning-band-distillation.html

10. Strategies Identification of the chemical structure of the off-note •  NMR spectroscopy: - Information about the chemical structure and chemicalenvironment of the molecules. But -Weneedmg to make the analysis.

11. Strategies 2) Tandem mass spectrometry (MS/MS): • Triple quadrupole mass spectrometer q= cell for collision-induced dissociation • Examine selectively the fragmentation of particular ions in a mixture of ions. • Structuralinformation => product ion scan. Inert gas forcollision Daughterion Parent ion Collision-inducedfragmentation

12. Strategies 3) GasChromatographyInfraredSpectrometry (GC-IR): • Separation of a mixture by a gaschromatograph. • The fractions containing a single compound are then steered towards a FTIR-spectrometer. Allows to identifyisomers

13. Strategies • Advantages: Very sensitive • Light pipes are heated in order to rid condensation and maximize path length for enhanced sensitivity • The interferogram can be obtained in a very brief time using a matrix isolation: Compared with the light pipes, the limit of detection can be reduced by a factor of about 100 Obtaining clear spectra of a sample ng

14. Strategies • Disadvantages: Veryexpensive • Matrix isolation needs a gold-flat and 10-12 K • Detector - highly sensitive

15. What are odorThreshold values (OTV)? • The lowest concentration of a certain odor  compound that is perceivable by the human sense of smell. • Can be expressed as a concentration in water or in air. • Optical isomers can have different detection thresholds and can be less perceivable for the human nose.

16. Odorthreshold values • Two major types of flavor thresholds can be distinguished: • The absolute odor threshold: The minimum quantity of an odorant to become perceptible. • The differential threshold: The minimum difference in odorant concentration that can be perceived as distinct.

17. Types of measurement • Psychophysicalmeasurements: • Single values obtainedfrom a series of repeteadmeasurementscarried out with one or severalindividuals.

18. Types of measurement • The dynamic dilution olfactometry (EN13725 standard): Odor concentration and odor threshold determination (ou/m3 = odor units per cubic meter of air) • Test sample: Ambient air, sampled continuously, batchwise from an odor-emitting source or an odorant-saturated gas. • Olfactometer presents the odour sample diluted with odour-free air at precise ratios, to a panel of human assessors. • The examiners selected with a standardized procedure performed using reference gases.

19. Types of measurement • GC sniffing technique: • Injection of different dilutions of a sample into the gas chromatograph until the perception of the substance at the sniffing port. • When the detector indicates its elution from the GC column • At the correct retention time.

20. Thankyouforyourattention