CBD isolate: what 99% means on a certificate

A CBD isolate is cannabidiol separated from everything else in the plant: minor cannabinoids, terpenes, flavonoids, waxes, chlorophyll. It comes as a white powder or as white crystals and assays, on certificates, at 99% CBD or more. It is the purest form of cannabidiol, and the one furthest removed from the hemp it came from.

That purification is possible because CBD is a crystalline solid at room temperature, whereas a whole extract stays an oil or a resin. "CBD crystals", "CBD powder" and "CBD 99" all name the same product, in coarser or finer grains or named after its assay; in every case, only the certificate of analysis says what is in the pouch. The article on full spectrum or isolate compares the two families from the point of view of use; here, the angle is the certificate.

Three stages, described without parameters or equipment.

Extraction. A solvent, most often supercritical CO₂ or ethanol, dissolves the compounds held in the trichomes. The crude extract still contains waxes, chlorophyll and every cannabinoid the variety carries.

Purification. The extract is stripped of its waxes by chilling (winterisation), then the cannabinoids are separated from the rest by distillation or chromatography. The distillate is concentrated in CBD, but keeps minor cannabinoids and part of the terpenes.

Crystallisation. The distillate is dissolved in a solvent in which the solubility of CBD varies sharply with temperature. As it cools, the CBD crystallises and the rest stays in solution; the crystals are washed, then dried. This stage takes the assay beyond 99%, removes the last terpenes and leaves in the powder a trace of the solvent used, which the certificate has to measure.

Full spectrum is defined in what full spectrum means. On its certificate, the information is the profile; on an isolate's certificate, it is the purity of a single peak and everything surrounding it.

4.1 Purity: percentage by mass or percentage of area

Cannabinoid content is measured by liquid chromatography with UV detection (HPLC-UV), the reference method in the monographs of several pharmacopoeias (Silva et al., 2025). The laboratory separates the molecules on a column and compares the area of the CBD peak with a calibration range built from a certified standard. The result is a percentage by mass: grams of CBD per 100 g of powder, written % m/m or % w/w.

Some certificates give a "chromatographic purity", as a percentage of area: the share of the CBD peak among all the peaks detected. That value ignores anything that does not absorb UV or does not come off the column, water, a residual solvent, a mineral residue. An isolate can show 99.8% of area and a lower assay by mass. When a certificate says 99%, the first question is the unit.

The second is uncertainty, which the ISO/IEC 17025 standard requires laboratories to evaluate. A validated HPLC method is not exact to the decimal: a validation published in 2022 reports recovery rates of 100 to 105% for CBD, inside the 90 to 110% window allowed by the ICH guidelines (Analakkattillam et al., 2022). Two certificates reading 99.2% and 99.6% can describe the same batch.

4.2 THC "not detected": a limit, not a zero

A properly purified isolate contains no measurable THC, and the certificate has to show it. But "ND" (not detected) and "< LOQ" (below the limit of quantification) do not mean zero: either the method sees nothing below a threshold, or it sees something it cannot put a figure on. A serious certificate states those thresholds, LOD and LOQ, cannabinoid by cannabinoid. Without them, "0% THC" is a label formula, not a result.

The French regime tolerates up to 0.30% Δ⁹-THC in an extract, but an isolate is sold precisely on the absence of THC: quantifiable THC signals incomplete purification, whatever the CBD percentage printed next to it. The guide on how to read a certificate of analysis covers the other headings.

4.3 Residual solvents: the line that separates certificates

The most common reference is the ICH Q3C guideline (version R9), written for pharmaceutical substances. It sorts solvents into three groups:

• Class 1, to be avoided: benzene, capped at 2 ppm.
• Class 2, to be limited: hexane at 290 ppm, methanol at 3 000 ppm.
• Class 3, low toxic potential: ethanol, pentane, heptane, 2-propanol, acetone; up to 50 mg per day, that is 5 000 ppm or 0.5%, acceptable without justification.

Three checks. Does the solvent looked for match the process? A certificate that only looks for ethanol says nothing about a pentane. Is the method named? Residual solvents are measured by headspace gas chromatography (GC-HS). Are the values given as figures? An "ND" per solvent, with its detection limit, is worth more than a "compliant" line with no number.

4.4 Terpenes, contaminants and the laboratory

An isolate has no terpene profile; a GC-MS panel comes back empty, and that is the expected result. Terpenes on an isolate's certificate signal an addition, which the label must state. Heavy metals (ICP-MS), pesticides (LC-MS/MS) and microbiology still have to be checked: a certificate measures them, it does not assume them.

That leaves the laboratory. ISO/IEC 17025:2017 accreditation attests the technical competence of a testing laboratory; in France, Cofrac grants it and its directory says who is accredited, and for which analyses. An ISO logo on a retail site does not replace that check, described in verifying a laboratory's accreditation. The certificate carries a batch number, a date and the laboratory's name; a "range" certificate with no batch commits nobody.

An isolate is a hemp extract within the meaning of the arrêté du 30 décembre 2021 (the French ministerial order on hemp): article 1, III caps the Δ⁹-THC content of extracts, and of the products that incorporate them, at 0.30%. The Conseil d'État (France's supreme administrative court), on 29 December 2022 (no. 444887), annulled the ban on selling raw flowers and leaves without touching that threshold. An isolate with undetected THC is far below it, but remains subject to the same certificate as any other extract.

Presented as a food, an isolate also falls under Regulation (EU) 2015/2283 on novel foods, which makes prior authorisation compulsory for any food not significantly consumed in the Union before 15 May 1997; EFSA received 19 applications for CBD and put their assessment on hold on 7 June 2022, for want of sufficient data. Phytogrammes products are not foodstuffs and are not intended for ingestion; this guide says nothing about how an isolate is used, only about its certificate.

Phytogrammes sells neither isolate nor CBD crystals. The catalogue is built on the whole plant, flowers, resins and full spectrum oils, every batch with its certificate, read on the our laboratory page in four blocks: cannabinoids, terpenes, metals, pesticides. The isolate question comes up often enough to deserve an answer; it belongs in the FAQ and in this guide, not in the shop.

• Phytogrammes, Canna·wiki "Cannabidiol"
• Légifrance, arrêté du 30 décembre 2021 (article 1, III)
• Conseil d'État, decision of 29 December 2022, no. 444887
• ISO/IEC 17025:2017, testing and calibration laboratories
• Cofrac, the French accreditation committee
• EMA, ICH Q3C (R9), residual solvents
• EUR-Lex, Regulation (EU) 2015/2283 on novel foods
• EFSA, cannabidiol novel food evaluations on hold, 7 June 2022
• Silva E. M. P. et al., "Recent HPLC-UV Approaches for Cannabinoid Analysis", Pharmaceuticals, 2025
• Analakkattillam S. et al., RP-HPLC validation of CBD and THC, Scientific Reports, 2022