As you know, there are many ways to adulterate an oil and as a result, nearly 80% of oils on the market are adulterated. One common oil, tea tree, or melaleuca, is often adulterated due to its high demand.
Different varieties of plants can create different oils. Just like one species of a plant can create a different oil than another species, the tea tree has two geographical varieties which produce different oils. The Chinese tea tree oil costs about half the price of the Australian oil. This leads to two common methods of adulteration: mixing the Chinese variety in with the Australian variety, or mislabeling Chinese as Australian.
Similar oils can be used to adulterate tea tree oil. Eucalyptus or its fractions, for example, is often used due to its chemical similarity to tea tree. Niaoli and camphor can also be used. By using similar oils or their fractions, producers can create “natural” oil without it being a pure oil. Carrier, vegetable, and cooking oils can also be used, however this form of adulteration is only to “water down” the main oil.
Natural compounds like terpinene-4-ol, Alpha-terpineol, Gamma-terpinene, Alpha-terpinene, or terpinolene can be used to create tea tree oil. By taking these constituents and mixing them together in the amounts set by ISO for a natural oil, sophisticated chemists can create tea tree oil right in the lab.
Due to the fact that it isn’t completely natural, the optical rotation will be different, as shown on a test run by an autoflex machine. Chemists will fix this by adding tiny amounts of d-limonene to get the correct physical constant from the optical rotation.
Synthetic Fossil-Fuel Based
Melaleuca oil is unique in that using synthetic fossil-fuel based components would not be economically beneficial. This makes adulteration less detectable than other oils since a carbon-based C-14 test will show no unusual results without a synthetic fossil-fuel based addition.
As evident here, there are many ways to adulterate some of the most common oils. Since only a chemist can analyze the test results of an oil, the best way to be sure your oil is pure is to have it tested by a legitimate third-party source.