Lemon verbena is a relatively rare oil with readily available components, which often leads to it being adulterated. The oil can be adulterated in the usual way with cooking oils, synthetics, such as synthetic citral, synthetic fragrances, or similar oils like lemongrass, litsea cubeba, or Spanish verbena.
Lemon verbena is unique in that it has 4 distinct chemotypes. Chemotypes are the chemical constituents that make up essential oils. In certain oils, multiple chemotypes are sometimes found. Different chemotypes are characterized by varying amounts of constituents. For example, Ho Leaf has three main chemotypes: camphor, cineole, and linalool. In the camphor type, camphor is present at 42.0–84.1%. In the Cineole type, 1,8-cineole is present at 56.7–63.7%. In the linalool type, linalool is present at 66.7–90.6%.
In lemon verbena, the main chemotypes are sabinene, limonene, thujone, and citral. With different chemotypes, adulteration is specifically catered to each chemotype. For example, if trying to adulterate the citral chemotype, adulterers make sure geranial is close to 30% and neral is near 23%, but in the sabinene chemotype, those percentages are closer to 10% each. Differences in chemotypes change the biological activities of the oil. Testing is essential to determine adulteration in all cases, however with different chemotypes, it becomes even more necessary.