Reading the numbers on a cannabinoid certificate of analysis

A certificate of analysis is only useful if the buyer can read every number on it in context. Two certificates can both say "CBD 99.2%" and describe materials that would behave differently in a formula, because the figure depends on the unit, the basis, the method and the limits behind it. This guide walks through the fields a B2B buyer should be able to interpret without help.

None of this replaces qualified laboratory or regulatory interpretation. It is meant to make a commercial review faster and to help a buyer ask the right question when a figure does not add up.

Potency units: % w/w, mg/g and mg per unit

Cannabinoid potency is usually reported as a mass fraction. 1% w/w equals 10 mg of cannabinoid per gram of material, so a CBD isolate at 99.2% w/w carries about 992 mg CBD per gram. Distillates are often reported the same way, while finished products may instead state mg per millilitre or mg per unit. Confirm the unit before comparing two offers, because a value in mg/mL and a value in % w/w are not directly comparable without the density or fill.

Watch for the reporting basis. Results can be given "as received" or on a dry-weight basis after moisture correction. For a near-anhydrous isolate the difference is small, but for a material with measurable moisture the dry-weight figure will read higher than the as-received figure for the same sample.

LOD and LOQ: what "not detected" really means

The limit of detection (LOD) is the lowest level a method can reliably distinguish from zero; the limit of quantification (LOQ) is the lowest level it can report as a number with acceptable accuracy. A result of "ND" or "not detected" means only that the analyte was below the LOD for that method, not that it is truly absent.

This matters most for controlled analytes. If a specification requires THC below a threshold, the method LOQ must sit comfortably below that threshold, otherwise a compliant-looking "ND" is meaningless. Always read the LOD and LOQ next to any result reported at or near zero.

The total-THC calculation

Raw cannabis analytics report both the neutral cannabinoid (THC) and its acidic precursor (THCA). Because THCA loses a carboxyl group and mass when it is heated, you cannot simply add the two figures. The accepted conversion is total THC = THC + (0.877 × THCA), and the same 0.877 decarboxylation factor is applied for total CBD = CBD + (0.877 × CBDA).

A buyer checking a delta-9 THC limit should confirm which figure the certificate reports. A material can show a low neutral-THC result yet exceed a total-THC limit once the THCA fraction is converted, so the wrong column can turn a rejected batch into an apparent pass.

Fields to reconcile before acceptance

Read these together rather than scanning for a single headline number.

Analyte, result, unit (% w/w, mg/g, mg/mL) and reporting basis

LOD and LOQ for each controlled analyte

Neutral versus total (decarboxylated) values where relevant

Method or method reference and whether it suits the matrix

Batch or lot number matched to the drum label

Sampling, receipt and analysis dates, and who submitted the sample

When the totals do not close

A quick sanity check is to add the reported cannabinoids and any moisture, residual solvent and ash figures. Totals that far exceed 100% suggest a unit or basis error; totals well below 100% on a claimed isolate suggest an unreported fraction worth questioning. Neither is proof of a problem, but both are a reason to ask the laboratory before the material is approved.