Analytical StrategyLynne Jiao Qinlei Liu Masha Naumenko

15.10.2019

Fragrances

Fragrances

Source

Provided Note

Chemical Structure

Animals

Plants

Lichens

Seaweed

Citruslemon, orange

Floralrose,

jasmine

Leather

leather,

tobacco

Woody

dry wood

Fruitypeach, apple

Greengrass, leaves

SpicycinnamonOriental

vanilla Animalmusk

Oxideseucalyptol

Estersmethyl

salicylate

KetonescyclohexanoneAlcohols

cis-3-hexenol

PhenolseugenolMonoterpene

hydrocarbons

limonene

Monoterpene

alcohols

lynalool

Terpeneketonesbeta-iononeTerpene

aldehydeseucalyptol

2Abedi G et al. Trends in Analytical Chemistry 102 (2018) 41-59

Common Fragrance Molecules

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TERPENOIDS CYCLIC MONOTERPENESTERPENOIDS

GERANIOL LINALOOL CITRONELLOL CITRONELLAL CITRAL L-CARVONE D-LIMONENE

Pybus, D.; Sell, C. The Royal Society of Chemistry (2006)

Same Functional Groups ? Same Odors

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TRUE FALSE

Enantiomers

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S-(-)-limonene R-(+)-limonene

ConcentrationSkatol

Concentration Increase

Olfaction Mechanisms

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OR 1 OR 2 OR 3

neurons

odorant molecules

receptors

A

B

A

B B

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Allergy

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limonene

Fragrances

Oxidation on air

Scientific Committee on Consumer Safety (SCCS) identified that 82 out of 3000 chemical substances are allergic !!!

primary oxidation products

Impurities

88

ProductionOxidation

Heavy metals impurities:

Cadmium (ore, sewage, Old batteries... )Lead (oil paint, electroplate, smelt... )Mercury (smelt, coal... )Nickel ( smelt, coal...)

1. Collection

2. Extraction

3. Blending

4. Aging

Fragrances Production

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NATURAL WAY SYNTHETIC WAY

Full synthetics

Semi-synthetics

Modify natural fragrancesby artificial means

Natural Way of Production

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COLLECTION BLENDINGEXTRACTION AGING

labile balance is finally achieved

approximately a month of waiting after mixing all ingredients into a perfume

Aged mixture is usually cooled, filtered and only after that filled into flacons

steam distillation

solvent extraction

blended according to the formula

determined by a “nose”

the scent is mixed with alcohol

usually 10-20% perfume oils dissolved in alcohol and a trace of water

Analytical Methods/ Quality ControlSensory Evaluation

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Expert/Trained Noses

Figure 1: Plots of mean intensity scores for sensory profile of six different craft beers evaluated by quantitative descriptive analysis using a 9-point scale.

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sample

olfactory receptor

electronic sensor array preprocessor

olfactory nerve

olfactory bulb

pattern recognition

Analytical Methods/ Quality ControlSensory EvaluationChemical sensor systems (“electronic noses”)

Figure 2: Mechanism of electronic nose in comparison to human olfactory system and a representative picture of electronic nose.

Analytical Methods/ Quality ControlSample Preparation

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MATRIX

LIQUID SEVERAL COSMETIC PRODUCTS

suntan oil, citrus oil, perfumes soaps, creams, lipsticks

DILUTION: methanol, ethanol, ACN, acetone, hexane, isooctane, 1-propanol, ethyl acetate

DIRECT ANALYSIS

DIFFICULT TO OBTAIN HOMOGENEOUS SOLUTION

DIFFERENT STRATEGIES OF SAMPLE PREPARATION

14Abedi G et al. Trends in Analytical Chemistry 102 (2018) 41-59

Classification and % for determination of fragrances in cosmetics and PCPs

Sample Preparation Methods

HS = HEADSPACE TECHNIQUES

SPE = SOLID PHASE EXTRACTION

LPE = LIQUID PHASE EXTRACTIONDILUTION

HS

TANDEM EXTRACTION METHODS

FREE SAMPLE PREPARATION

LPESPE

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HS Sample Preparation

Volatile molecules migrate into headspace phase

Heavy molecules remain in liquid phase

Headspace

Perfume sample

GC

PEAK OF INTEREST

PEAK OF INTEREST

▪ IR (Infrared Radiation)

▪ MS (Mass Spectrometry)

▪ NMR (Nuclear Magnetic Resonance)

▪ Sniff / E-nose (Sensory Evaluation)

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Analytical Methods

▪ GC

▪ LC

Instruments used for identification

Instruments used for separation

Analytical Methods for Fragrances Determination

GC: gas chromatographyHPLC: high performance liquid chromatographyCE: capillary electrophoresisEN: electronic nose

Abedi G et al. Trends in Analytical Chemistry 102 (2018) 41-59

FS: fluorescence spectroscopyNMR: nuclear magnetic resonance spectroscopyMS: mass spectrometry

Analytical Methods

Most commonly used separation and identification methods

▪ GC-MS:

▪ LC-MS：

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gas: He, N2, H2

sample injector column

syringe pump

column

mass spectrometer

ion source

Mass Analyzer

Detector

mass spectrometer

ion source

Mass Analyzer

Detector

GC-MS vs LC-MS

1919

GC-MS LC-MS

●Simultaneous analysis of multiple compounds

●High sensitivity

●Easy analysis of volatile and thermally stable compounds

●Simultaneous analysis of multiple compounds

●Wide application range

●Samples are easy to recycle

●Limited to the analysis of volatile and thermally stable substances

●More expensive than GC-MS

●Less sensitive than GC-MS

Problem 1

R-(+)-limonene

How to check the purity of R-(+)-limonene? How does the purity affect the odor profile?

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ENANTIOMERS SEPARATION WITH CHIRAL COLUMN

OPTICAL ROTATION MEASUREMENTS

▪ Differing intermolecular attractions - separation of enantiomers

▪ Most chiral GC and HPLC columns utilize a starch derived polysaccharide (cyclodextrin) as the chiral stationary phase.

IMPURITY - smell changes - LEMON NOTES ADDED?

Problem 2What is the legal situation of fragrance allergens in cosmetic products? Which analytical technique would you choose to screen for allergenic substances in raw materials?

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▪ Scientific Committee on Consumer Safety is responsible for supervising the fragrance allergens in cosmetic products.

▪ The legal situation of fragrance allergens in cosmetic products is that if the 26 fragrance allergens exceed 0.001% (leave-on cosmetic products) / 0.01% (rinse-off cosmetic products), the 26 fragrance allergens are required to be labelled in cosmetic products to alerts consumers to avoid the risk of sensitization that may occur.

Solution 2What is the legal situation of fragrance allergens in cosmetic products?

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Solution 2Which analytical technique would you choose to screen for allergenic substances in raw materials?

GC-MS

Problem: EI usually produces a lot of fragment ions, and the molecular ion is often absent or of very low intensity.

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Solution 2Which analytical technique would you choose to screen for allergenic substances in raw materials?

▪ Another possibility：we will choose GC-DBDI-MS to screen for allergenic substances in raw materials.

Mirabelli MF., Zenobi R. et al. Analyst, 2017, 142(11), 1909-1915. 24

Solution 2A new type of soft ionization source developed in Zenobi group - Active Capillary Plasma Ionization (Dielectric Barrier Discharge Ionization, DBDI)

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Cross section of the plasma source

Two electrodes are separated with glass capillary which is the insulating (dielectric) layer to stop the current and prevent spark formation. A high AC voltage is applied to one of the electrodes to generate a plasma.

Solution 2The advantages of GC-DBDI-MS to screen for allergenic substances● Since the allergenic substances with varying polarities, volatility and odor thresholds，DBDI

source can ionize polar, mid-polarity, as well as non-polar compounds;

● The “active capillary ionization” developed in Zenobi group has good sensitivity, softness and low cost.

The source is connected directly to the inlet capillary of the mass spectrometer to achieve 100 % transport efficiency of the ions.

Mirabelli MF., Zenobi R. et al. Analyst, 2017, 142(11), 1909-1915 26

Problem 3

R-(+)-limonene

What is the analytical challenge when analysing limonene hydroperoxides (mainly limonene-2-OOH)? How would you quantitatively analyse limonene hydroperoxides in deodorants or cremes?

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● ChallengeThe analytical challenges to quantitatively analyse limonene-2-OOH in fragrance products are multi-faceted:

-Sensitivity is an issue using GC-MS. The hydroperoxides are not very stable at GC-MS injection conditions; therefore, the less sensitive split mode has to be applied. Also, limonene-2-OOH tends to show peak broadening on the GC column. -The selectivity of detection for cis/trans-limonene-2-OOH is hampered by unspecific fragment ions in complex sample matrices.

● Quantitative AnalysisReduction method offers a first pragmatic and practical approach to study limonene hydroperoxide levels in hydroalcoholic products. A method based on selective reduction of limonene-2-OOH to carveol by triphenylphosphine (PPh3) is established. This is followed by GC-MS.

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