CPTG Certified Pure Tested Grade® is doTERRA's proprietary quality protocol, a sequence of analytical and physical tests applied to doTERRA essential oils before reaching consumers. doTERRA developed the CPTG® standard because no universally enforced regulatory definition of "pure" exists in the essential oil industry. This testing protocol includes gas chromatography, mass spectrometry, Fourier transform infrared spectroscopy (FTIR), chiral analysis, carbon isotope analysis, microbial screening, heavy metal testing, and organoleptic evaluation. GC/MS results from doTERRA's internal, state-of-the-art laboratory are separately verified by Aromatic Plant Research (APRC) and are published at sourcetoyou.com, where consumers can look up test results by bottle lot number.
A pure essential oil is unadulterated, which means three things: First, it’s sourced from nature rather than synthetically produced in a lab. Second, it’s authentic. Its botanical identity is verified through testing, confirming that it is what it says it is. Third, it’s undiluted by fillers or additives. It contains no undisclosed ingredients like fragrances, dyes, or preservatives.
Essential oils are not regulated under a single, internationally consistent purity standard. Terms like "100% pure" and "natural" carry no legally binding definition in most markets. Industry estimates suggest that a large percentage of commercially available essential oils have been adulterated in some form, whether diluted with carrier oils, extended with synthetic aromatic chemicals or blended with cheaper botanical substitutes.
Adulteration matters for practical reasons. Synthetic linalool produced in a laboratory, for example, creates a racemic mixture, an even 50/50 ratio of left-handed and right-handed molecular forms. Linalool produced by a living plant, by contrast, tends toward one dominant enantiomer. Chiral gas chromatography can distinguish between the two. Without that test, a customer has no way to know whether the linalool in a bottle came from a Lavender field in Bulgaria or a chemical plant.
Gas chromatography coupled with mass spectrometry (GC/MS) has long been considered the baseline analytical tool for essential oils. But GC/MS alone has limits and may miss certain forms of adulteration, particularly when a synthetic additive is structurally identical to a naturally occurring compound.
doTERRA's CPTG protocol was designed to address these limitations through redundancy: no single test carries the burden of confirming quality alone.
doTERRA's CPTG quality protocol includes eight distinct analytical and evaluative methods, organized into four testing categories: chemistry, physical properties, contamination screening and stability verification.
Organoleptic evaluation is the first checkpoint. Trained distillers and chemists assess the visual appearance, aroma, color and consistency of each batch using human senses. An unusual smell, uneven texture or atypical color can signal contamination or degradation before laboratory instruments are ever engaged. Organoleptic assessment serves as a preliminary filter, and a batch that fails this step does not advance to chemical analysis.
Gas chromatography separates an essential oil into its individual chemical constituents. A sample is vaporized and carried by an inert gas (typically helium) through a long, narrow column coated in a stationary-phase material. Each molecular component travels through the column at a different speed depending on its weight and polarity, producing a chromatogram, which is a graph that maps each constituent by its retention time. Scientists compare the chromatogram's peaks against known reference standards to verify that the expected compounds are present and in the correct proportions.
Mass spectrometry identifies the chemical structure of each component separated during gas chromatography. After the GC column separates the oil's constituents, each one is ionized and passed through magnetic fields. Differences in molecular weight and charge allow the spectrometer to produce a structural fingerprint for each compound. GC and MS are used in tandem, and together they confirm both the identity and concentration of every constituent in a batch.
FTIR passes infrared light of varying frequencies through an essential oil sample and measures how much light is absorbed. Each compound absorbs infrared radiation in a characteristic pattern, creating a molecular fingerprint. doTERRA compares these fingerprints against a historical database of absorption patterns from batches that met quality standards. FTIR can catch discrepancies that GC/MS alone might miss, particularly structural anomalies in the oil's compound profile.
Many essential oil compounds exist as mirror-image molecular pairs called enantiomers, structurally identical but oriented in opposite directions, like left and right hands. Plants produce these enantiomers in specific, predictable ratios. Synthetic versions of the same compounds typically produce a 50/50 racemic mixture. Chiral gas chromatography measures the ratio of left-to-right enantiomers in a sample. A ratio that deviates from the expected natural pattern signals synthetic adulteration.
Carbon exists in two stable isotopic forms: carbon-12 and carbon-13. Plants produce organic compounds with a characteristic ratio of these isotopes. Petrochemical synthetics carry a different isotopic signature. Isotope-ratio mass spectrometry measures the carbon-13 to carbon-12 ratio in an essential oil sample to detect petroleum-derived additives. doTERRA uses this test selectively to confirm that compounds are biologically derived rather than synthetically manufactured.
Microbial screening checks for fungi, bacteria, viruses and mold. A sample is placed in a sterile growth medium and incubated. After a set period, the medium is inspected for microbial colonies. doTERRA performs this test both on raw oil arriving at the manufacturing facility and on finished product before distribution, confirming that no contamination occurred during the bottling process.
Inductively coupled plasma mass spectrometry (ICP-MS) ionizes the essential oil sample in a high-energy plasma field and runs it through a mass spectrometer to detect trace metals. ICP-MS identifies the presence and quantity of any heavy metals introduced through soil, equipment, and handling.
doTERRA's in-house laboratory employs more than 20 scientists and occupies 2,200 square feet of dedicated testing space. But in-house testing alone cannot satisfy the standard of independent verification. doTERRA contracts with the Aromatic Plant Research Center (APRC), a respected lab based in Lehi, Utah, that focuses exclusively on aromatic plant testing and research.
APRC uses internationally recognized analytical methods, including GC/MS and GC-FID, and serves numerous clients globally. APRC's executive advisory board includes scientists with doctoral-level credentials in organic chemistry, biochemistry and pharmacognosy.
doTERRA publishes individual GC/MS quality reports for every single-oil bottle produced since May 2016 through its Source to You platform. Consumers enter the Quality ID printed on the bottom of each bottle to access:
doTERRA is the only APRC client that makes its third-party testing results available to the public through an open-access platform.
doTERRA's essential oil science team is led by Prabodh Satyal, who holds a doctorate in chemistry from the University of Alabama in Huntsville. Satyal has studied the chemical compositions of more than 100,000 essential oils globally and has published more than 200 peer-reviewed research articles. His Google Scholar profile shows more than 4,200 citations across his body of work.
Satyal has a particular focus on adulteration detection. He has created what doTERRA describes as the only known mass spectral library of synthetic markers, a reference database used to identify the chemical signatures of common adulterants. He is developing the first fully automated GC/MS adulteration analysis software, which would identify the purity percentage, geographic origin and blended sources in a given essential oil sample.
Nicole Stevens, doTERRA's vice president of clinical research, holds a doctorate in biochemistry and molecular biology from the University of Miami Miller School of Medicine. Stevens has led studies examining how essential oil compounds are metabolized in the human body, work that has produced novel findings on essential oil metabolic, proteomic and epigenetic mechanisms.
doTERRA scientists presented research at the 23rd Annual International Conference on the Science of Botanicals (ICSB) in May 2025. Satyal shared findings on essential oil degradation, and Stevens presented research on the chemistry and biochemistry of Copaiba volatile oil, including what doTERRA described as the first published human data on Copaiba ingestion.
CPTG testing confirms quality at the laboratory level, but doTERRA's position is that quality assurance begins at the point of cultivation. doTERRA sources more than 140 essential oils from more than 40 countries through its Cō-Impact Sourcing® program, a model that establishes long-term partnerships with farmers, harvesters and distillers.
Cō-Impact Sourcing prioritizes growing plants in their native or ideal environments. Bulgarian Lavender, for example, is sourced from Bulgaria. In many cases, doTERRA works directly with growers rather than purchasing through brokers or commodity traders. That direct relationship gives doTERRA's quality team closer oversight of cultivation, harvest timing and distillation practices, all variables that affect the final chemical profile of an essential oil before it ever reaches a laboratory.
CPTG stands for certified pure tested grade. It is a registered trademark of doTERRA Holdings, LLC, and refers to the company's proprietary quality testing protocol for essential oils. CPTG is not a government certification or an industry-wide standard. It is doTERRA's internal protocol, applied to every batch the company produces.
Eight primary analytical and evaluative methods form the core of the CPTG protocol: organoleptic evaluation, gas chromatography, mass spectrometry, FTIR spectroscopy, chirality testing, carbon isotope analysis, microbial screening and heavy metal testing via ICP-MS.
Yes. doTERRA publishes GC/MS quality reports for every single-oil bottle produced since May 2016 at sourcetoyou.com. Enter the Quality ID printed on the bottom of the bottle to view the report.
Gas chromatography/mass spectrometry, or GC/MS, is an analytical method that separates an essential oil into its individual chemical constituents (via gas chromatography) and then identifies each constituent's molecular structure (via mass spectrometry). GC/MS is widely considered the baseline analytical tool for essential oil quality control.
doTERRA uses chirality testing and carbon isotope analysis alongside standard GC/MS to detect synthetic adulteration. Chirality testing measures enantiomer ratios, the balance between left-handed and right-handed molecular forms, which differ between plant-derived and lab-synthesized compounds. Carbon isotope analysis detects petroleum-derived chemicals by measuring the ratio of carbon-13 to carbon-12 in a sample.
CPTG Certified Pure Tested Grade is not a government regulation or a third-party industry certification. It is a proprietary quality standard developed and maintained by doTERRA. No external regulatory body administers the CPTG label.
