Perfume or parfum is a mixture of fragrant essential oils or aroma compounds, fixatives and solvents used to give the human body, animals, objects, and living spaces "a pleasant scent." The odoriferous compounds that make up a perfume can be manufactured synthetically or extracted from plant or animal sources.
Perfumes have been known to exist in some of the earliest human civilizations, either through ancient texts or from archaeological digs. Modern perfumery began in the late 19th century with the commercial synthesis of aroma compounds such as vanillin or coumarin, which allowed for the composition of perfumes with smells previously unattainable solely from natural aromatics alone.
The word perfume used today derives from the Latin per fumum, meaning "through smoke." Perfumery, or the art of making perfumes, began in ancient Mesopotamia and Egypt and was further refined by the Romans and Persians.
The world's first recorded chemist is considered to be a woman named Tapputi, a perfume maker who was mentioned in a cuneiform tablet from the 2nd millennium BC in Mesopotamia. She distilled flowers, oil, and calamus with other aromatics then filtered and put them back in the still several times.
In 2005, archaeologists uncovered what are believed to be the world's oldest perfumes in Pyrgos, Cyprus. The perfumes date back more than 4,000 years. The perfumes were discovered in an ancient perfumery. At least 60 stills, mixing bowls, funnels and perfume bottles were found in the 43,000-square-foot (4,000 m2) factory. In ancient times people used herbs and spices, like almond, coriander, myrtle, conifer resin, bergamot, as well as flowers.
The Arab chemist, Al-Kindi (Alkindus), wrote in the 9th century a book on perfumes which he named Book of the Chemistry of Perfume and Distillations. It contained more than a hundred recipes for fragrant oils, salves, aromatic waters and substitutes or imitations of costly drugs. The book also described 107 methods and recipes for perfume-making and perfume making equipment, such as the alembic (which still bears its Arabic name).
The Persian chemist Ibn Sina (also known as Avicenna) introduced the process of extracting oils from flowers by means of distillation, the procedure most commonly used today. He first experimented with therose. Until his discovery, liquid perfumes were mixtures of oil and crushed herbs or petals, which made a strong blend. Rose water was more delicate, and immediately became popular. Both of the raw ingredients and distillation technology significantly influenced western perfumery and scientific developments, particularly chemistry.
The art of perfumery was known in western Europe ever since 1221, if we consider the monks' recipes of Santa Maria delle Vigne or Santa Maria Novella of Florence, Italy. In the east, the Hungarians produced in 1370 a perfume made of scented oils blended in an alcohol solution at the command of Queen Elizabeth of Hungary, best known as Hungary Water. The art of perfumery prospered in Renaissance Italy, and in the 16th century, Italian refinements were taken to France by Catherine de' Medici's personal perfumer, Rene the Florentine (Renato il fiorentino). His laboratory was connected with her apartments by a secret passageway, so that no formulae could be stolen en route. Thanks to Rene, France quickly became one of the European centers of perfume and cosmetic manufacture. Cultivation of flowers for their perfume essence, which had begun in the 14th century, grew into a major industry in the south of France. Between the 16th and 17th century, perfumes were used primarily by the wealthy to mask body odors resulting from infrequent bathing. Partly due to this patronage, the perfumery industry was created. In Germany, Italian barber Giovanni Paolo Feminis created a perfume water called Aqua Admirabilis, today best known as eau de cologne, while his nephew Johann Maria Farina (Giovanni Maria Farina) in 1732 took over the business. By the 18th century, aromatic plants were being grown in the Grasse region of France, in Sicily, and in Calabria, Italy to provide the growing perfume industry with raw materials. Even today, Italy and France remain the center of the European perfume design and trade.
Perfume types reflect the concentration of aromatic compounds in a solvent, which in fine fragrance is typically ethanol or a mix of water and ethanol. Various sources differ considerably in the definitions of perfume types. The intensity and longevity of a perfume is based on the concentration, intensity and longevity of the aromatic compounds (natural essential oils / perfume oils) used: As the percentage of aromatic compounds increases, so does the intensity and longevity of the scent created. Specific terms are used to describe a fragrance's approximate concentration by percent/volume of perfume oil, which are typically vague or imprecise. A list of common terms (Perfume-Classification) is as follows:
- Perfume extract, or simply perfume (extrait): 15-40% (IFRA: typical 20%) aromatic compounds
- Esprit de Parfum (ESdP): 15-30% aromatic compounds, a seldom used strength concentration in between EdP and perfume
- Eau de Parfum (EdP), Parfum de Toilette (PdT): 10-20% (typical ~15%) aromatic compounds, sometimes listed as "eau de perfume" or "millésime." Parfum de Toilette is a less common term that is generally analogous to Eau de Parfum.
- Eau de Toilette (EdT): 5-15% (typical ~10%) aromatic compounds
- Eau de Cologne (EdC): Chypre citrus type perfumes with 3-8% (typical ~5%) aromatic compounds. "Original Eau de Cologne" is a registered trademark.
- Perfume mist: 3-8% aromatic compounds (typical non-alcohol solvent)
- Splash (EdS) and aftershave: 1-3% aromatic compounds. "EdS" is a registered trademark.
A "Classical cologne" describes men's and women's fragrances "which are basically citrus blends and do not have a perfume parent". Classical colognes are different from modern colognes, where the fragrance is typically a lighter, less concentrated interpretation of a perfume. Men's colognes are also different from women's colognes. Men's colognes have a similar concentration to eau de toilette, eau de parfum, "and in some instances perfume"; women's colognes, on the other hand, are often the lightest concentration from a line of women's fragrance products.
Although quite often Eau de Parfum (EdP) will be more concentrated than Eau de Toilette (EdT) and in turn Eau de Cologne (EdC), this is not always the case. Different perfumeries or perfume houses assign different amounts of oils to each of their perfumes. Therefore, although the oil concentration of a perfume in EdP dilution will necessarily be higher than the same perfume in EdT from within the same range, the actual amounts can vary between perfume houses. An EdT from one house may be stronger than an EdP from another.
Men's fragrances are rarely sold as EdP or perfume extracts; equally so, women's fragrances are rarely sold in EdC concentrations. Although this gender specific naming trend is common for assigning fragrance concentrations, it does not directly have anything to do with whether a fragrance was intended for men or women. Furthermore, some fragrances with the same product name but having a different concentration name may not only differ in their dilutions, but actually use different perfume oil mixtures altogether. For instance, in order to make the EdT version of a fragrance brighter and fresher than its EdP, the EdT oil may be "tweaked" to contain slightly more top notes or fewer base notes. In some cases, words such asextrême, intense, or concentrée that might indicate aromatic concentration are actually completely different fragrances, related only because of a similar perfume accord. An example of this is Chanel's Pour Monsieur and Pour Monsieur Concentrée.
Eau de Cologne (EdC) since 1706 in Cologne, Germany, is originally a specific fragrance and trademark. However outside of Germany the term has become generic for Chypre citrus perfumes (without base-notes). EdS (since 1993) is a new perfume class and a registered trademark.
The conventional application of pure perfume (parfum extrait) in Western cultures is at pulse points, such as behind the ears, the nape of the neck, and the insides of wrists, elbows and knees, so that the pulse point will warm the perfume and release fragrance continually. The modern perfume industry encourages the practise of layering fragrance so that it is released in different intensities depending upon the time of the day. Lightly scented products such as bath oil, shower gel, and body lotion are recommended for the morning; eau de toilette is suggested for the afternoon; and perfume applied to the pulse points for evening. Cologne fragrance is released rapidly, lasting around 2 hours. Eau de toilette lasts from 2 to 4 hours, while perfume may last up to six hours.
A variety of factors can influence how fragrance interacts with the wearer's own physiology and affect the perception of the fragrance. Diet is one factor, as eating spicy and fatty foods can increase the intensity of a fragrance. The use of medications can also impact the character of a fragrance. The relative dryness of the wearer's skin is important, since dry skin will not hold fragrance as long as skin with more oil.Fragrance notes
Perfume is described in a musical metaphor as having three sets of notes, making the harmonious scent accord. The notes unfold over time, with the immediate impression of the top note leading to the deeper middle notes, and the base notes gradually appearing as the final stage. These notes are created carefully with knowledge of the evaporation process of the perfume.
- Top notes: The scents that are perceived immediately on application of a perfume. Top notes consist of small, light molecules that evaporate quickly. They form a person's initial impression of a perfume and thus are very important in the selling of a perfume. Also called the head notes.
- Middle notes: The scent of a perfume that emerges just prior to when the top notes dissipate. The middle note compounds form the "heart" or main body of a perfume and act to mask the often unpleasant initial impression of base notes, which become more pleasant with time. They are also called the heart notes.
- Base notes: The scent of a perfume that appears close to the departure of the middle notes. The base and middle notes together are the main theme of a perfume. Base notes bring depth and solidity to a perfume. Compounds of this class of scents are typically rich and "deep" and are usually not perceived until 30 minutes after application.
The scents in the top and middle notes are influenced by the base notes, as well the scents of the base notes will be altered by the type of fragrance materials used as middle notes. Manufacturers of perfumes usually publish perfume notes and typically they present it as fragrance pyramid, with the components listed in imaginative and abstract terms
The traditional classification which emerged around 1900 comprised the following categories:
- Single Floral: Fragrances that are dominated by a scent from one particular flower; in French called a soliflore. (e.g. Serge Lutens' Sa Majeste La Rose, which is dominated by rose.)
- Floral Bouquet: Is a combination of fragrance of several flowers in a perfume compound. Examples include Quelques Fleurs by Houbigant and Joy by Jean Patou.
- Ambered, or "Oriental": A large fragrance class featuring the sweet slightly animalic scents of ambergris or labdanum, often combined with vanilla, tonka bean, flowers and woods. Can be enhanced by camphorous oils and incense resins, which bring to mind Victorian era imagery of the Middle East and Far East. Traditional examples include Guerlain's Shalimar and Yves Saint Laurent's Opium.
- Wood: Fragrances that are dominated by woody scents, typically of agarwood, sandalwood and cedarwood. Patchouli, with its camphoraceous smell, is commonly found in these perfumes. A traditional example here would be Myrurgia's Maderas De Oriente or Chanel Bois-des-Îles. A modern example would be Balenciaga Rumba.
- Leather: A family of fragrances which features the scents of honey, tobacco, wood and wood tars in its middle or base notes and a scent that alludes to leather. Traditional examples include Robert Piguet's Bandit and Balmain's Jolie Madame.
- Chypre (IPA: [ʃipʁ]): Meaning Cyprus in French, this includes fragrances built on a similar accord consisting of bergamot, oakmoss, patchouli, and labdanum. This family of fragrances is named after a perfume by François Coty, and one of the most famous examples is Guerlain's Mitsouko.
- Fougère (IPA: [fu.ʒɛʁ]): Meaning Fern in French, built on a base of lavender, coumarin and oakmoss. Houbigant's Fougère Royale pioneered the use of this base. Many men's fragrances belong to this family of fragrances, which is characterized by its sharp herbaceous and woody scent. Some well-known modern fougères are Fabergé Brut and Guy Laroche Drakkar Noir.
Since 1945, due to great advances in the technology of perfume creation (i.e., compound design and synthesis) as well as the natural development of styles and tastes, new categories have emerged to describe modern scents:
- Bright Floral: combining the traditional Single Floral & Floral Bouquet categories. A good example would be Estée Lauder's Beautiful.
- Green: a lighter and more modern interpretation of the Chypre type, with pronounced cut grass, crushed green leaf and cucumber-like scents. Examples include Estée Lauder's Aliage, Sisley's Eau de Campagne, and Calvin Klein's Eternity.
- Aquatic, Oceanic, or Ozonic: the newest category in perfume history, first appearing in 1988 Davidoff Cool Water (1988), Christian Dior's Dune (1991), and many others. A clean smell reminiscent of the ocean, leading to many of the modernandrogynous perfumes. Generally contains calone, a synthetic scent discovered in 1966, or other more recent synthetics. Also used to accent floral, oriental, and woody fragrances.
- Citrus: An old fragrance family that until recently consisted mainly of "freshening" eau de colognes, due to the low tenacity of citrus scents. Development of newer fragrance compounds has allowed for the creation of primarily citrus fragrances. A good example here would be Faberge Brut.
- Fruity: featuring the aromas of fruits other than citrus, such as peach, cassis (black currant), mango, passion fruit, and others. A modern example here would be Ginestet Botrytis.
- Gourmand (French: [ɡuʁmɑ̃]): scents with "edible" or "dessert"-like qualities. These often contain notes like vanilla, tonka bean and coumarin, as well as synthetic components designed to resemble food flavors. A sweet example is Thierry Mugler's Angel. A savory example would be Dinner by BoBo, which has cumin and curry hints.
The fragrance wheel
The Fragrance wheel is a relatively new classification method that is widely used in retail and in the fragrance industry. The method was created in 1983 by Michael Edwards, a consultant in the perfume industry, who designed his own scheme of fragrance classification. The new scheme was created in order to simplify fragrance classification and naming scheme, as well as to show the relationships between each of the individual classes.
The five standard families consist of Floral, Oriental, Woody, Fougère, and Fresh, with the former four families being more "classic" while the latter consisting of newer bright and clean smelling citrus and oceanic fragrances that have arrived due to improvements in fragrance technology. Each of the families are in turn divided into sub-groups and arranged around a wheel.
Aromatic sourcesPlant sources
Plants have long been used in perfumery as a source of essential oils and aroma compounds. These aromatics are usually secondary metabolites produced by plants as protection against herbivores, infections, as well as to attract pollinators. Plants are by far the largest source of fragrant compounds used in perfumery. The sources of these compounds may be derived from various parts of a plant. A plant can offer more than one source of aromatics, for instance the aerial portions and seeds of coriander have remarkably different odors from each other. Orange leaves, blossoms, and fruit zest are the respective sources of petitgrain, neroli, and orange oils.
- Bark: Commonly used barks includes cinnamon and cascarilla. The fragrant oil in sassafras root bark is also used either directly or purified for its main constituent, safrole, which is used in the synthesis of other fragrant compounds.
- Flowers and blossoms: Undoubtedly the largest and most common source of perfume aromatics. Includes the flowers of several species of rose and jasmine, as well as osmanthus, plumeria, mimosa, tuberose, narcissus, scented geranium,cassie, ambrette as well as the blossoms of citrus and ylang-ylang trees. Although not traditionally thought of as a flower, the unopened flower buds of the clove are also commonly used. Most orchid flowers are not commercially used to produce essential oils or absolutes, except in the case of vanilla, an orchid, which must be pollinated first and made into seed pods before use in perfumery.
- Fruits: Fresh fruits such as apples, strawberries, cherries unfortunately do not yield the expected odors when extracted; if such fragrance notes are found in a perfume, they are synthetic. Notable exceptions include litsea cubeba, vanilla, andjuniper berry. The most commonly used fruits yield their aromatics from the rind; they include citrus such as oranges, lemons, and limes. Although grapefruit rind is still used for aromatics, more and more commercially used grapefruit aromatics are artificially synthesized since the natural aromatic contains sulfur and its degradation product is quite unpleasant in smell.
- Leaves and twigs: Commonly used for perfumery are lavender leaf, patchouli, sage, violets, rosemary, and citrus leaves. Sometimes leaves are valued for the "green" smell they bring to perfumes, examples of this include hay and tomato leaf.
- Resins: Valued since antiquity, resins have been widely used in incense and perfumery. Highly fragrant and antiseptic resins and resin-containing perfumes have been used by many cultures as medicines for a large variety of ailments. Commonly used resins in perfumery include labdanum, frankincense/olibanum, myrrh, Peru balsam, gum benzoin. Pine and fir resins are a particularly valued source of terpenes used in the organic synthesis of many other synthetic or naturally occurring aromatic compounds. Some of what is called amber and copal in perfumery today is the resinous secretion of fossil conifers.
- Roots, rhizomes and bulbs: Commonly used terrestrial portions in perfumery include iris rhizomes, vetiver roots, various rhizomes of the ginger family.
- Seeds: Commonly used seeds include tonka bean, carrot seed, coriander, caraway, cocoa, nutmeg, mace, cardamom, and anise.
- Woods: Highly important in providing the base notes to a perfume, wood oils and distillates are indispensable in perfumery. Commonly used woods include sandalwood, rosewood, agarwood, birch, cedar, juniper, and pine. These are used in the form of macerations or dry-distilled (rectified) forms.
- Ambergris: Lumps of oxidized fatty compounds, whose precursors were secreted and expelled by the sperm whale. Ambergris should not be confused with yellow amber, which is used in jewelry. Because the harvesting of ambergris involves no harm to its animal source, it remains one of the few animalic fragrancing agents around which little controversy now exists.
- Castoreum: Obtained from the odorous sacs of the North American beaver.
- Civet: Also called Civet Musk, this is obtained from the odorous sacs of the civets, animals in the family Viverridae, related to the mongoose. The World Society for the Protection of Animalsinvestigated African civets caught for this purpose.
- Hyraceum: Commonly known as "Africa Stone", is the petrified excrement of the Rock Hyrax.
- Honeycomb: From the honeycomb of the honeybee. Both beeswax and honey can be solvent extracted to produce an absolute. Beeswax is extracted with ethanol and the ethanol evaporated to produce beeswax absolute.
- Deer musk: Originally derived from the musk sacs from the Asian musk deer, it has now been replaced by the use of synthetic musks sometimes known as "white musk".
Many modern perfumes contain synthesized odorants. Synthetics can provide fragrances which are not found in nature. For instance, Calone, a compound of synthetic origin, imparts a fresh ozonous metallic marine scent that is widely used in contemporary perfumes. Synthetic aromatics are often used as an alternate source of compounds that are not easily obtained from natural sources. For example, linalool and coumarin are both naturally occurring compounds that can be inexpensively synthesized from terpenes. Orchid scents (typically salicylates) are usually not obtained directly from the plant itself but are instead synthetically created to match the fragrant compounds found in various orchids.
One of the most commonly used class of synthetic aromatic by far are the white musks. These materials are found in all forms of commercial perfumes as a neutral background to the middle notes. These musks are added in large quantities to laundry detergents in order to give washed clothes a lasting "clean" scent.
The majority of the world's synthetic aromatics are created by relatively few companies. They include:
- International Flavors and Fragrances (IFF)
Each of these companies patents several processes for the production of aromatic synthetics annually
Obtaining natural odrants
Before perfumes can be composed, the odorants used in various perfume compositions must first be obtained. Synthetic odorants are produced through organic synthesis and purified. Odorants from natural sources require the use of various methods to extract the aromatics from the raw materials. The results of the extraction are either essential oils, absolutes, concretes, or butters, depending on the amount of waxes in the extracted product.
All these techniques will, to a certain extent, distort the odor of the aromatic compounds obtained from the raw materials. This is due to the use of heat, harsh solvents, or through exposure to oxygen in the extraction process which will denature the aromatic compounds, which either change their odor character or renders them odorless.
- Maceration/Solvent extraction: The most used and economically important technique for extracting aromatics in the modern perfume industry. Raw materials are submerged in a solvent that can dissolve the desired aromatic compounds.Maceration lasts anywhere from hours to months. Fragrant compounds for woody and fibrous plant materials are often obtained in this manner as are all aromatics from animal sources. The technique can also be used to extract odorants that are too volatile for distillation or easily denatured by heat. Commonly used solvents for maceration/solvent extraction include hexane, and dimethyl ether. The product of this process is called a "concrete."
- Supercritical fluid extraction: A relatively new technique for extracting fragrant compounds from a raw material, which often employs Supercritical CO2. Due to the low heat of process and the relatively nonreactive solvent used in the extraction, the fragrant compounds derived often closely resemble the original odor of the raw material.
- Ethanol extraction: A type of solvent extraction used to extract fragrant compounds directly from dry raw materials, as well as the impure oily compounds materials resulting from solvent extraction or enfleurage. Ethanol extraction is not used to extract fragrance from fresh plant materials since these contain large quantities of water, which will also be extracted into the ethanol.
- Distillation: A common technique for obtaining aromatic compounds from plants, such as orange blossoms and roses. The raw material is heated and the fragrant compounds are re-collected throughcondensation of the distilled vapour.
- Steam distillation: Steam from boiling water is passed through the raw material, which drives out their volatile fragrant compounds. The condensate from distillation are settled in a Florentine flask. This allows for the easy separation of the fragrant oils from the water. The water collected from the condensate, which retains some of the fragrant compounds and oils from the raw material is called hydrosol and sometimes sold. This is most commonly used for fresh plant materials such as flowers, leaves, and stems.
- Dry/destructive distillation: The raw materials are directly heated in a still without a carrier solvent such as water. Fragrant compounds that are released from the raw material by the high heat often undergo anhydrous pyrolysis, which results in the formation of different fragrant compounds, and thus different fragrant notes. This method is used to obtain fragrant compounds from fossil amber and fragrant woodswhere an intentional "burned" or "toasted" odor is desired.
- Fractionation: Through the use of a fractionation column, different fractions distilled from a material can be selectively excluded to modify the scent of the final product. Although the product is more expensive, this is sometimes performed to remove unpleasant or undesirable scents of a material and affords the perfumer more control over their composition process.
- Expression: Raw material is squeezed or compressed and the oils are collected. Of all raw materials, only the fragrant oils from the peels of fruits in the citrus family are extracted in this manner since the oil is present in large enough quantities as to make this extraction method economically feasible.
- Enfleurage: Absorption of aroma materials into solid fat or wax and then extraction of odorous oils with ethyl alcohol. Extraction by enfleurage was commonly used when distillation was not possible because some fragrant compounds denature through high heat. This technique is not commonly used in the modern industry due to prohibitive costs and the existence of more efficient and effective extraction methods.
Although fragrant extracts are known to the general public as the generic term "essential oils", a more specific language is used in the fragrance industry to describe the source, purity, and technique used to obtain a particular fragrant extract.
Of these extracts, only absolutes, essential oils, and tinctures are directly used to formulate perfumes.
- Absolute: Fragrant materials that are purified from a pommade or concrete by soaking them in ethanol. By using a slightly hydrophilic compound such as ethanol, most of the fragrant compounds from the waxy source materials can be extracted without dissolving any of the fragrantless waxy molecules. Absolutes are usually found in the form of an oily liquid.
- Concrete: Fragrant materials that have been extracted from raw materials through solvent extraction using volatile hydrocarbons. Concretes usually contain a large amount of wax due to the ease in which the solvents dissolve various hydrophobic compounds. As such concretes are usually further purified through distillation or ethanol based solvent extraction. Concretes are typically either waxy or resinous solids or thick oily liquids.
- Essential oil: Fragrant materials that have been extracted from a source material directly through distillation or expression and obtained in the form of an oily liquid. Oils extracted through expression are sometimes called expression oils.
- Pomade: A fragrant mass of solid fat created from the enfleurage process, in which odorous compounds in raw materials are adsorbed into animal fats. Pommades are found in the form of an oily and sticky solid.
- Tincture: Fragrant materials produced by directly soaking and infusing raw materials in ethanol. Tinctures are typically thin liquids.
Products from different extraction methods are known under different names even though their starting materials are the same. For instance, orange blossoms from Citrus aurantium that have undergone solvent extraction produces "orange blossom absolute" but that which have been steam distilled is known as "neroli oil".
The job of composing perfumes that will be sold is left up to an expert on perfume composition or known in the fragrance industry as the perfumer. They are also sometimes referred to affectionately as a "Nez" (French for nose) due to their fine sense of smell and skill in smell composition.
The composition of a perfume typically begins with a brief by the perfumer's employer or an outside customer. The customers to the perfumer or their employers, are typically fashion houses or large corporations of various industries. The perfumer will then go through the process of blending multiple perfume mixtures and sell the formulation to the customer, often with modifications of the composition of the perfume.
Perfume oils usually contain tens to hundreds of ingredients and these are typically organized in a perfume for the specific role they will play. These ingredients can be roughly grouped into four groups:
- Primary scents (Heart): Can consist of one or a few main ingredients for a certain concept, such as "rose". Alternatively, multiple ingredients can be used together to create an "abstract" primary scent that does not bear a resemblance to a natural ingredient. For instance, jasmine and rose scents are commonly blends for abstract floral fragrances. Cola flavourant is a good example of an abstract primary scent.
- Modifiers: These ingredients alter the primary scent to give the perfume a certain desired character: for instance, fruit esters may be included in a floral primary to create a fruity floral; calone and citrus scents can be added to create a "fresher" floral. The cherry scent in cherry cola can be considered a modifier.
- Blenders: A large group of ingredients that smooth out the transitions of a perfume between different "layers" or bases. These themselves can be used as a major component of the primary scent. Common blending ingredients include linalool and hydroxycitronellal.
- Fixatives: Used to support the primary scent by bolstering it. Many resins, wood scents, and amber bases are used as fixatives.
The top, middle, and base notes of a fragrance may have separate primary scents and supporting ingredients. The perfume's fragrance oils are then blended with ethyl alcohol and water, aged in tanks for several weeks and filtered through processing equipment to, respectively allow the perfume ingredients in the mixture to stabilize and to remove any sediment and particles before the solution can be filled into the perfume bottles.
Creating perfumes through reverse engineering with analytical techniques such as Gas chromatography–mass spectrometry (GC/MS) can reveal the "general" formula for any particular perfume. The difficulty of GC/MS analysis arises due to the complexity of a perfume's ingredients. This is particularly due to the presence of natural essential oils and other ingredients consisting of complex chemical mixtures. However, "anyone armed with good GC/MS equipment and experienced in using this equipment can today, within days, find out a great deal about the formulation of any perfume... customers and competitors can analyze most perfumes more or less precisely."
Antique or badly preserved perfumes undergoing this analysis can also be difficult due to the numerous degradation by-products and impurities that may have resulted from breakdown of the odorous compounds. Ingredients and compounds can usually be ruled out or identified using gas chromatograph (GC) smellers, which allow individual chemical components to be identified both through their physical properties and their scent. Reverse engineering of best-selling perfumes in the market is a very common practice in the fragrance industry due to the relative simplicity of operating GC equipment, the pressure to produce marketable fragrances, and the highly lucrative nature of the perfume market.
In some cases, an excessive use of perfumes may cause allergic reactions of the skin. For instance, acetophenone, ethyl acetate and acetone while present in many perfumes, are also known or potential respiratory allergens. Nevertheless this may be misleading, since the harm presented by many of these chemicals (either natural or synthetic) is dependent on environmental conditions and their concentrations in a perfume. For instance, linalool, which is listed as an irritant, causes skin irritation when it degrades to peroxides, however the use of antioxidants in perfumes or reduction in concentrations can prevent this. As well, the furanocoumarin present in natural extracts of grapefruit or celery can cause severe allergic reactions and increase sensitivity to ultraviolet radiation.
There is scientific evidence that nitro-musks such as musk xylene can cause cancer while common ingredients, like certain polycyclic synthetic musks, can disrupt the balance of hormones in the human body (endocrine disruption). Some natural aromatics, such as oakmoss absolutes, contain allergens and carcinogenic compounds.
Some research on natural aromatics have shown that many contain compounds that cause skin irritation. However some studies, such as IFRA's research claim that opoponax is too dangerous to be used in perfumery, still lack scientific consensus. It is also true that sometimes inhalation alone can cause skin irritation.
Certain chemicals found in perfume are often toxic, at least for small insects if not for humans. For example the compound Tricyclodecenyl allyl ether is often found in synthetic perfumes and has insect repellent property.
Synthetic musks are pleasant in smell and relatively inexpensive, as such they are often employed in large quantities to cover the unpleasant scent of laundry detergents and many personal cleaning products. Due to their large-scale use, several types of synthetic musks have been found in human fat and milk, as well as in the sediments and waters of the Great Lakes.
These pollutants may pose additional health and environmental problems when they enter human and animal diets.
The demands for aromatic materials like sandalwood, agarwood, musk has led to the endangerment of these species as well as illegal trafficking and harvesting.