Natural isolate

Natural linalool is separated from the linalool type of ho, Cinnamomum camphora, and earlier from rosewood, Aniba rosaeodora. Eugenol comes from clove leaf oil: the oil is washed with an alkaline solution, eugenol forms a water-soluble salt, the non-phenolic part is separated off, and eugenol is released again with acid.

Citral is fractionally distilled from may chang (Litsea cubeba). Geraniol and citronellal come from Java citronella. Menthol is crystallised by chilling cornmint oil (Mentha arvensis); the remaining oil is sold as dementholised mint oil.

Cedrol crystallises from Texas and Virginia cedarwood oils. 1,8-Cineole is distilled from eucalyptus. Anethole is separated from star anise by chilling until it crystallises.

Safrole was once isolated from sassafras and related trees as a feedstock for heliotropin (piperonal). Safrole is now in Table I of the 1988 UN Convention on drug precursors, and is banned in EU cosmetics except for its natural content in essential oils, up to 100 ppm in the finished product.

EU Regulation (EC) 1334/2008 on food flavourings, Article 3, defines a natural flavouring substance as one naturally present and identified in nature, obtained by physical, enzymatic or microbiological processes from material of plant, animal or microbial origin. Linalool isolated from ho wood meets this definition; linalool synthesised from petroleum does not. The regulation dropped the nature-identical category of earlier law; a substance is either natural or simply a flavouring substance. Article 16 adds a further tier: a natural X flavouring label requires at least 95 percent of the flavouring component to come from source X.

ISO 9235:2021 has no dedicated entry for isolates. It defines a natural raw material as material of plant, animal or microbial origin obtained by physical, enzymatic or microbiological processes or by preparation such as extraction, distillation, heating, roasting or fermentation.

For cosmetics, ISO 16128-1:2016 and ISO 16128-2:2017 define natural and derived natural ingredients and set out how to calculate a product's natural index and natural origin index. Both are voluntary guidelines, not law, and require no certification.

Under EU REACH, essential oils, absolutes and resinoids are treated as natural complex substances (NCS): multi-constituent substances identified by their botanical source and the process that made them. ECHA places most NCS in the UVCB category. The joint EFEO and IFRA guidelines of 2015 describe how to identify NCS and establish their sameness.

An isolate sits on the other side of that line. Once a compound is separated to high purity, it is registered as a mono-constituent substance, like its synthetic twin, even though its origin is a plant.

Chiral GC measures the ratio of the two optical isomers. Plants usually make one isomer in excess, while ordinary synthesis yields a 50 to 50 racemic mixture. Linalool from ho wood is mainly the (R)-(−) form.

Carbon 14 separates modern carbon from fossil carbon. A compound synthesised from petroleum holds almost no carbon 14. The test cannot tell an isolate from a compound synthesised from another plant feedstock, such as turpentine.

IRMS measures ratios of stable isotopes such as carbon 13 and deuterium; SNIF-NMR measures deuterium at each position in the molecule. Together they can separate vanillin from vanilla pods from vanillin made from lignin or guaiacol, and show whether the source plant uses C3 or C4 photosynthesis. The review by Do and colleagues (2015) describes these tests for essential oils.

An isolate smells of one molecule plus traces of its parent oil. Linalool from ho may keep a faint camphor note; citral from may chang carries traces of the oil's other compounds. A pure synthetic carries traces of its chemical route instead. Neither is safer by default: IFRA limits and EU allergen rules apply to the molecule, whatever its source.