In the previous articles, we discussed about basics of adulteration in essential oils and test to be performed to find out adulteration in essential oils. Continuing the series in adulteration of essential oils, here we are going to discuss examples of adulteration in essential oils.
Basil oil ct. methyl chavicol is adulterated with synthetic methyl chavicol and such adulteration can be detected with NMR. Basil oil ct. linalool is adulterated with synthetic linalool and is usually detected by chiral separation.
Bergamot oil is adulterated with synthetic linalool, linalyl acetate, bergamot terpenes and distilled oil from bergamot peel residue. It is also blended with limonene, nerol, geranyl acetate, rosewood oil and citral from Litsea cubeba oil.
Cajeput oil is adulterated with oils from various other Melaleuca species, e.g. Niaouli and Liniment tree, and with Eucalyptus, Camphor, Rosemary or Lavender oils. It may also be blended with eucalyptus terpenes, α -phellandrene and α –terpineoI. Adulteration is usually detected by GC/MS.
Caraway oil is adulterated with synthetic carvone and limonene.
Cardamom oil is adulterated with 1,8-cineole from eucalyptus or camphor oil, α –terpinyl acetate and linalool. It is hard to discover adulteration with 1,8-cineole. In case cardamom oil is adulterated with synthetic terpinyl acetate, it can be detected with presence of δ -terpinyl acetate.
Cassia oil is adulterated with synthetic cinnamaldehyde and coumarin.
Celery Seed Oil
Celery seed oil is blended with α -terpineol, limonene from orange oil, rectified copaiba oil, lovage root oil and amyris oil. Adulteration is detected with GC-MS tests.
Chamomile, Blue Oil
Blue chamomile oils are adulterated with synthetic α -bisabolol, chamazulene, and (E)-β farnesene.
Chamomile, Roman Oil
Roman chamomile oil is adulterated with synthetic angelates and esters such as isobutyl angelate, 2-methylbutyl angelate, isobutyl isobutyrate, methyl 2-methylbutyrate, prenyl acetate, 2-methylbutyl 2-methylbutyrate and 2-methylbutyl acetate. Adulteration is detected with GC-C-IRMS.
Cinnamon Bark Oil
Cinnamon bark oil is adulterated with cheaper cassia oil. However, adulteration of cinnamon oil with cassia oil is easily detectable by presence of coumarin, a compound found in cassia oil and not in cinnamon bark oil.
Cinnamon bark oil is also adulterated with synthetic cinnamaldehyde, which can be detected with GC-C-IRMS and GC-P-IRMS tests.
Cinnamon Leaf Oil
Cinnamon leaf oil is adulterated with rectified clove leaf oil or isolated eugenol from clove leaf oil. In addition, β -caryophyllene, synthetic benzyl benzoate and trans- cinnamaldehyde may be added to adulterate. Blending is done with α -terpineol.
Synthetic citronellal, citronellol, and geraniol are used to adulterate citronella oil.
There are 3 different types of clove oils depending upon the biomass used to extract the oils – bud, leaf or stem. Out of all these oils, clove bud is most expensive and usually is adulterated with clove leaf or clove stem oils. And, lesser expensive leaf and stem oils may also be adulterated with residues from isolation of natural eugenol. Adulteration is detected with GC-MS tests.
Coriander oil may be adulterated with linalool.
Corn Mint Oil
Corn mint oil is adulterated with synthetic menthol, menthyl acetate and menthone, terpenes and limonene. Adulteration is detected using GC-MS.
Cumin oil is blended with cuminaldehyde, orange terpenes, p-cymene and piperitone. Adulteration is detected using GC-MS and by the combination of GC-C-IRMS and GC-P-IRMS to detect the presence of synthetic and natural cuminaldehyde.
Cypress oil is adulterated with either turpentine oil or α – and β -pinene. Further, blending is done using δ-3-carene and cedrol from cedarwood Chinese type.
Dill seed oil is adulterated with phellandrenes, limonene from orange terpenes, synthetic carvone and dihydrocarvone. Adulteration is detected using 2D enantiomeric separation.
Eucalyptus oil is adulterated with 1,8-cineole from various Cinnamomum varieties. It is difficult to detect such adulteration in eucalyptus oil.
Fennel, Sweet Oil
Sweet fennel oil is adulterated with synthetic anethole or from other sources like star anise oil. Blending is done too with star anise oil and limonene. Adulteration can be detected with GC-MS or by multidimensional enantiomeric separation.
Geranium oil is blended with synthetic geraniol, citronellol, limonene, terpinyl formate, synthetic rhodinol, α -terpineol cristallin and distilled bergamot oil.
Grapefruit oil is blended with nootkatone, together with n-octanal, n-nonanal, n-decanal and synthetic citral. Adulteration is performed by orange terpenes and distilled grapefruit residues from expression and limonene. Adulteration is detected using multidimensional enantiomeric separation.
Lavandin oils is adulterated with acetylated lavandin, lavandin distilled heads and tails, camphor oil white, Spanish sage oil and spike lavender oil. Blending is done with synthetic terpinyl acetate, turpentine oil, methyl α -terpineol and ethyl amyl ketone, hexyl ketone and geranyl acetate.
Lavender oil is adulterated with cheaper lavandin oils, spike lavender oil, rectified Ho oil, acetylated lavandin oils, etc.
Lemon oil is adulterated with distilled lemon oil from residues, orange terpenes or limonene from orange terpenes and synthetic citral from Litsea cubeba oil. Blending is done by using synthetic decanal, nonanal, octanal and citronellal from Corymbia citriodora oil. Detection is made by GC-MS and mainly by multidimensional enantiomeric separation.
Lemongrass oil is adulterated with synthetic citral or citral from Litsea cubeba oil. Blending is done with addition of geranyl acetate and 6-methyl-5-heptene-2-one. Detection is carried out with GC-MS and multidimensional chiral separation.
Lime oil is blended with limonene, citral from Litsea cubeba oil and γ -terpinene from lime terpenes. Adulteration is detected using GC-MS and multidimensional enantiomeric separation methods.
May Chang Oil
May Chang oil is adulterated with synthetic citral and is usually tested using GC-MS.
Mandarin oil is adulterated with synthetic methyl-n -methyl anthranilate and methyl anthranilate. It may also be blended with orange terpenes and limonene, dipentene, citronellal, and citral. Adulteration is detected with GC-MS.
Melissa oil is adulterated with citronella oil, lemongrass oil, lemon oil citral and geraniol rose oxides.
Neroli oil is adulterated with geraniol from palmarosa oil, linalool from rose wood oil, orange oil sweet, citral from Litsea cubeba oil. It is also blended with methyl-n -methyl anthranilate, methyl anthranilate, synthetic phenyl ethyl alcohol, and synthetic indol. Detection is carried out with GC-MS and multidimensional chiral separation.
Nutmeg oil is adulterated with monoterpenes α– and β-pinene, sabinene, α- and β-phellandrene and synthetic linalool, terpinen-4-ol and α -terpineol. Adulteration in nutmeg oil is detected with GC-MS.
Orange Bitter Oil
Bitter orange oil is adulterated with sweet orange oil, terpenes and distilled bitter orange residues. Addition of sweet orange oil is detected by δ -3-carene and camphene content.
Orange Sweet Oil
Sweet orange oil is adulterated with orange terpenes or purified limonene.
Oregano oil is adulterated with synthetic thymol and carvacrol or with limonene from different sources.
Palmarosa oil is adulterated with synthetic geraniol and detection is performed with the combination of GC-C-IRMS and GC-P-IRMS.
Parsley oil is adulterated with turpentine oil or pure α-pinene, β-pinene, and elemicin from elemi resinoid. It is also blended with celery grain oil, nutmeg oil and carrot seed oil. Adulteration is detected with GC-MS system.
Patchouli oil is adulterated with gurjun balm oil and may also blended with patchouli terpenes, cedarwood oil, pepper oil, white camphor oil and guaiac wood oil. Adulteration is detected with GC-MS.
Pepper Black Oil
Black pepper oil is blended with turpentine oil, α-phellandrene, limonene from orange terpenes and clove leaf oil terpenes.
Peppermint oil is adulterated with synthetic menthol, menthol from corn mint oil and fractions of peppermint terpenes. Adulteration is detected with chiral separation using 2D enantiomeric columns on GC-MS system.
Rose oil is blended with synthetic phenyl ethyl alcohol, synthetic rhodinol and geraniol from palmarosa oil. Rose oil may also be blended with geranium oil, ylang oil, rose absolute and palmarosa oil. Adulteration is detected with GC-MS and chiral separation with multidimensional GC-MS.
Rosemary oil is blended with turpentine oil, synthetic camphor and limonene from orange terpenes. Rosemary oil is also adulterated with 1,8-cineole from eucalyptus or white camphor oil. Adulteration is detected with GC-MS and multidimensional chiral separation.
Rosewood oil is blended with synthetic linalool, α-terpineol, geraniol and heads of rosewood oil. Adulteration is detected with GC-MS on a chiral column.
Spearmint oil is adulterated with synthetic levo-carvone and adulteration is detected with enantiomeric separation by GC-MS.
Spike Lavender Oil
Spike lavender oil is adulterated with white camphor oil, 1,8-cineole distilled from eucalyptus oil, synthetic camphor and linalool. In addition, it may also be blended with terpenes from eucalyptus oil, turpentine oil, n-bornyl acetate, lavandin, rosemary oil, HO leaf oil and α-terpineol. Adulteration is detected with GC-MS and by multidimensional chiral separation.
Tea Tree Oil
Tea tree oil is adulterated with α-pinene, β-pinene, γ-terpinene and synthetic terpinen-4-ol. Purity test is carried out with GC-MS and by using multidimensional chiral analytical equipment.
Ylang-ylang oil is adulterated with either by one of the fractions of cananga oil (extra, first, second or third) or with various fractions like heads and tails. It is blended with linalyl acetate, benzyl acetate, synthetic geraniol, methyl benzoate, benzyl alcohol, methyl salicylate, etc. Purity may be detected with GC/MS and by multidimensional chiral separation.