Part 4: Quality Testing—Isotopic Analysis

The building blocks from which we and all matter are made are chemical elements. A wide variety of elements exist that possess different characteristics and properties. Each element contains three components: protons, neutrons, and electrons. Each element is distinguished from other elements by the number of protons (and electrons) it contains. The number of protons always matches the number of electrons. An isotope occurs when the number of protons is the same but the element has a different number of neutrons. Each element is naturally found in one or more stable isotopic forms; for example, carbon has two stable isotopes, carbon-12 (which has 6 neutrons) and carbon-13 (which has 7 neutrons). Both forms have 6 protons and electrons. Because essential oils are organic compounds, they are composed primarily of carbon atoms and will have a certain ratio of carbon-12 to carbon-13. This ratio varies based on location around the world.

Carbon-12 and carbon-13 have similar chemical characteristics in the physical world, but at the atomic level, even a single neutron affects the mass of the atom, and in turn, the molecular weight of molecules they are part of. Use of a special type of mass spectroscopy makes it possible to determine which isotopes are present in an essential oil constituent and at what amounts because of these differences in atomic mass. If sourced from the same location, every constituent in an essential oil should have the same ratio of isotopes (such as 99 percent carbon-12 and 1 percent carbon-13). If a particular essential oil constituent has an isotopic profile different than that of the other constituents (such as 98 percent carbon-12 and 2 percent carbon-13), it tells the scientist that the oil contains an adulteration from another location.