Understanding C14 Carbon Testing for Essential Oils
- Jovine Marcella Kurniawan
- 16 minutes ago
- 3 min read
C14 carbon testing (also known as radiocarbon analysis or carbon-14 isotope testing) is a scientific method used to determine whether a substance originates from natural plant sources or from petrochemical (synthetic) sources. Every living plant absorbs carbon dioxide from the atmosphere during its life cycle, including a small amount of radioactive carbon-14 (¹⁴C). After a plant dies, the amount of ¹⁴C slowly decreases due to radioactive decay. In contrast, petrochemical compounds—derived from ancient fossil sources like petroleum—contain no detectable ¹⁴C, because the isotope has completely decayed over millions of years.
By measuring the level of ¹⁴C in a sample, scientists can accurately determine whether the material is:
100% biogenic (natural origin) = 100% Modern Carbon
100% synthetic (petrochemical origin) = 0% Modern Carbon
A mixture of both (% Modern Carbon in range between 0-100%)
The word “natural” in cosmetics, perfumery, and essential oils isn’t just a marketing term — it’s guided by the ISO 16128 standard. ISO 16128 defines what counts as natural or naturally derived based on origin and processing:
Natural Ingredient: comes directly from plant, mineral, or animal sources, obtained only by physical, enzymatic, or microbial processes (e.g., distillation, extraction, expression, fermentation). No intentional chemical modification of the molecule.
Naturally Derived Ingredient: made from natural starting materials through limited chemical reactions allowed by the standard (e.g., esterification, hydrogenation, hydrolysis), as long as the carbon atoms remain 100% biogenic (confirmed by C14 analysis if needed).
In addition, both EU and US “natural” materials can have 100% modern carbon, but only EU natural products meet specific process definitions.
In the essential oil and fragrance industry, where “natural” and “synthetic” materials can have nearly identical chemical structures, traditional analytical tools like GC–MS cannot always distinguish whether an ingredient was derived from plants or from petrochemical sources. The percentage of modern carbon revealed by C14 testing depends on the origin of the raw materials used to produce the essential oil or natural isolate, for example in Geranyl acetate:
When both geraniol and ethyl acetate are natural, derived entirely from plant sources such as citronellal oil and bio-fermentation ethanol, all the carbon atoms in the molecule come from recent biological material, giving a result of approximately 100% modern carbon. This confirms a fully biogenic and EU-natural product under ISO 16128.
However, if natural geraniol is esterified using synthetic ethyl acetate from petrochemical feedstock, only ten out of the twelve carbon atoms in geranyl acetate are biogenic. The C14 test in this case would show around 83% modern carbon, indicating that the material is mostly natural but not fully compliant with EU “natural” standards due to the fossil-derived acetyl component.
Conversely, when synthetic geraniol is combined with natural ethyl acetate, only two of the twelve carbons are biogenic, yielding roughly 17% modern carbon, which classifies it as mostly synthetic.
Finally, when both geraniol and ethyl acetate are fully synthetic, the result drops to 0% modern carbon, confirming a completely fossil-derived product. These differences illustrate how C14 testing can precisely quantify the biogenic content of a fragrance material, distinguishing between truly natural, partially natural, and synthetic origins even when the molecules are chemically identical.
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