Essential Oils 101: Purity, Quality & Safety
What Makes an Oil "Pure"?
Purity is not a marketing claim—it is a measurable property. For Lavandula angustifolia, purity is the linalyl acetate to linalool ratio. For Melaleuca alternifolia, it is Terpinen-4-ol meeting ISO 4730. For Citrus limon, it is the absence of phototoxic furocoumarins above safe thresholds.
Essential Oil Grades: What the Labels Mean
Therapeutic grade is not a regulated term. Fragrance grade oils are often extended with solvents. Organic certification verifies pesticide-free growing but not chemical profile. The safest approach is to specify botanical name and chemical marker ranges, verified against GC/MS data.
Adulteration: The Hidden Risk
Common methods include extension with synthetic isolates, cross-contamination with cheaper species, carrier oil dilution, and synthetic terpene re-blending. Detection requires high-resolution GC/MS with chiral column analysis and IRMS for botanical origin verification.
Dilution Math for Formulators
General guideline: 0.5–2% for leave-on skincare, 2–4% for rinse-off, 3–5% for therapeutic massage, up to 10% for acute topical applications under professional guidance. Always use weight-based measurements.
Storage Protocols
Essential oils degrade above 25°C, with oxidation rates doubling per 10°C increase. Store in amber glass, 18–22°C, with argon blanketing for bulk. Shelf life: citrus 1–2 years, floral 2–3 years, wood 4–6 years.