| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Angelica archangelica | Plant | -- | -- | Pakistan Encyclopedia Planta Medica. 1986. | |
| Citrus sinensis | Root Bark | -- | 24000.0 | Jim Duke's personal files. | |
| Citrus sinensis | Root | -- | -- | Jim Duke's personal files. | |
| Citrus limon | Root | -- | -- | Jim Duke's personal files. | |
| Citrus paradisi | Root | -- | -- | CRC Handbook of Medicinal Herbs and/or CRC Handbook of Proximate Analyses | |
| Citrus reticulata | Root | -- | -- | * | |
| Zanthoxylum americanum | Plant | -- | -- | * | |
| Zanthoxylum americanum | Stem Bark | -- | -- | * | |
| Zanthoxylum americanum | Bark | -- | -- | Williamson, E. M. and Evans, F. J., Potter's New Cyclopaedia of Botanical Drugs and Preparations, Revised Ed., Saffron Walden, the C. W. Daniel Co., Ltd., Essex UK, 362 pp, 1988, reprint 1989. | |
| Zanthoxylum americanum | Root Bark | -- | -- | * |