For international cannabis buyers, potency labelling on a Canadian Certificate of Analysis looks straightforward until it isn't. A batch showing 28% THC on one document and 32% THCA on another is not a contradiction. It reflects two different reporting standards, two different testing moments, and two different regulatory frameworks that your supply chain must reconcile before you sign a purchase agreement.
THCA and THC represent the same molecule at different points in the decarboxylation process. How your supplier reports them, and how your local regulator expects to see them declared, directly affects import permit compliance, pharmacy shelf labelling, and the batch comparisons you use to evaluate supplier consistency. Getting this right is a procurement decision, not just a chemistry question.
This guide explains the science clearly, maps the reporting conventions across the German, Australian, and Israeli medical channels, and shows what to check on a COA before committing to a supply agreement.
The decarboxylation equation explained
The cannabis plant synthesises THCA (tetrahydrocannabinolic acid), the acidic, non-intoxicating precursor to THC. THCA converts to THC through heat, a process called decarboxylation. Raw dried flower contains almost entirely THCA, with only trace THC present from ambient temperature exposure during curing.
When a lab analyses fresh dried flower using high-performance liquid chromatography (HPLC), it reports the compound as it exists in the plant: THCA. When the same sample is analysed using gas chromatography (GC), the heat of the instrument converts THCA to THC before measurement, and the result is reported as THC. Neither method is wrong. They are measuring the same underlying quantity at different chemical states.
The conversion factor most regulators and labs use is the decarboxylation formula:
Total THC = (THCA x 0.877) + THC
The 0.877 multiplier accounts for the molecular weight lost when the carboxyl group is released as CO2 during decarboxylation. For a batch reporting 32% THCA and 0.5% THC, the total THC equivalent is (32 x 0.877) + 0.5 = approximately 28.6%.
This is why the same flower can appear at 32% on an HPLC-based COA and 28-29% on a GC-based report. B2B buyers who compare supplier COAs without knowing which method was used are comparing incompatible numbers.
How Canadian exporters report potency (and why it matters to you)
Health Canada's Cannabis Regulations require Licensed Producers to report both THCA and THC values on Cannabis Act-compliant labelling. Canadian labs almost universally use HPLC for dried flower analysis, because GC degrades certain cannabinoids during thermal vaporisation and produces less reliable results for full-spectrum profiling.
What this means for import partners: a Canadian COA will show THCA as the dominant value, with a relatively small THC figure alongside it. The total THC equivalent is derived using the 0.877 formula, and most Health Canada-compliant batch summaries include this calculated figure explicitly.
When evaluating a Canadian supplier's COA, look for these three data points:
- Reported THCA (as a percentage of dry weight)
- Reported delta-9-THC (typically 0.2% to 1.5% for fresh dried flower)
- Total THC equivalent (THCA x 0.877 + THC)
If a COA shows only a single THC figure with no THCA column, ask the lab whether GC or HPLC was used before drawing conclusions about potency relative to other suppliers. A 28% GC result and a 28% HPLC result are not equivalent: the HPLC figure would convert to roughly 24.5% total THC equivalent, while the GC figure is already a post-decarboxylation number.
Regulatory expectations by market (Germany, Australia, Israel)
How potency must be declared varies by jurisdiction. B2B buyers need to match the Canadian COA to the labelling standard their local regulator enforces.
| Market | Reporting standard | Preferred method | Key regulator | Total THC formula required? |
|---|---|---|---|---|
| Germany | Total THC equivalent for pharmacy dispensing; THCA and THC both listed on import documentation | HPLC preferred | BfArM / Bundesopiumstelle | Yes |
| Australia | Total THC equivalent per TGO 93; THCA declared alongside delta-9-THC on Schedule 8 product label | HPLC | TGA / ODC | Yes |
| Israel | IMC-GMP-compliant COA must show THCA, THC, and the calculated total cannabinoid profile | HPLC | Israel Medical Cannabis Agency | Yes |
For German buyers, BfArM's narcotic import permit applications require potency figures consistent with the export documentation from Health Canada. Discrepancies between the Canadian COA and the German import documentation can trigger a customs hold. Your Canadian supplier's QA team should be familiar with this and able to issue a supplementary COA formatted to Bundesopiumstelle standards if needed.
For Australian buyers, TGO 93 sets specific requirements for how cannabinoid content is expressed on the product label. The ODC and TGA both expect the THCA and THC figures to be traceable to the original batch COA from the LP. Buyers importing from Canada should request that each batch COA includes an explicit total THC calculation alongside the raw HPLC values.
For Israeli buyers, the IMC-GAP and IMC-GMP frameworks require a full cannabinoid matrix on every COA, including THCA, delta-9-THC, delta-8-THC, CBD, CBDA, CBG, and CBGA at minimum. The Israel Medical Cannabis Agency expects these to be reported from an accredited laboratory, ideally ISO/IEC 17025 certified, so the data is traceable and court-defensible.
What to verify on a COA before signing a supply agreement
Treating a COA as a compliance formality is a procurement risk. The following five checks should be standard practice when evaluating a new Canadian supplier.
The B2B Buyer's 5-Point COA Potency Check
- Confirm the testing method. HPLC or GC? If the COA does not state the method, request the lab's method sheet. The two methods produce non-comparable raw figures.
- Verify lab accreditation. The issuing lab should hold ISO/IEC 17025 accreditation for cannabis testing. Accreditation scope should include cannabinoid potency by HPLC. Certificates of Accreditation are public documents you can verify directly.
- Check the total THC calculation. Is the formula (THCA x 0.877) + THC explicitly applied? If the COA only shows one potency line, that is a red flag for procurement, regardless of whether the number looks right.
- Review batch-to-batch consistency. Request COAs for the last three to five batches of the same cultivar. Variance in total THC equivalent of more than 2-3 percentage points across batches suggests inconsistent growing or harvesting practices.
- Confirm the sample date and test date. Cannabinoid content degrades over time, particularly under poor storage conditions. A COA issued 8 to 12 months before delivery may not reflect the potency of what arrives. Request a re-test COA on delivery if the original test is more than six months old.
See our full guide to reading a cannabis certificate of analysis for a complete breakdown of every COA field a B2B buyer should understand before signing.
Potency is not just a compliance number. For B2B buyers running medical cannabis programmes, consistent potency across successive deliveries is a clinical reliability question. Pharmacy dispensaries, medical distributors, and hospital formularies depend on predictable product profiles because their prescribing and dosing guidance is calibrated to the expected range.
A supplier who can deliver 28-30% total THC equivalent across six consecutive batches of the same cultivar is a fundamentally different supply partner than one who ranges from 22% to 31%. The COA tells you where any single batch landed. The batch history tells you whether that batch is representative.
When requesting historical COAs from a prospective supplier, ask for:
- A minimum of three consecutive batches of the specific cultivar you intend to purchase
- The corresponding harvest date, cure duration, and storage conditions for each batch
- Any batch failures or re-tests, with the original and final COA included
Suppliers who are reluctant to share batch history, or who can only provide COAs for the specific batch being offered, are worth treating with additional scrutiny. Consistency is the hard part of indoor cannabis cultivation, and transparent suppliers know it. For a broader framework on evaluating Canadian suppliers, see our B2B cannabis supplier evaluation guide.
AlphaLeaf is a Montreal-based Licensed Producer of indoor-grown, hand-trimmed cannabis flower operating under a Health Canada Standard Cultivation licence. Our ISO/IEC 17025-certified batch testing produces full-panel COAs that include THCA, total THC equivalent, and a complete cannabinoid and terpene matrix. We hold export authorisation under the Cannabis Act and maintain the COA documentation, traceability records, and quality system alignment that German, Australian, and Israeli import partners require for the medical channel.
Frequently Asked Questions
What is the difference between THCA and THC on a cannabis COA?
THCA is the acidic precursor found in raw dried flower; THC is the compound it converts to when heated. Most Canadian COAs report THCA as the primary potency figure because labs use HPLC, which measures the compound before decarboxylation. Total THC equivalent is calculated as (THCA x 0.877) + THC. B2B buyers should always check which figure is being used when comparing suppliers.
Why does a Canadian COA show a different potency number than my local pharmacy label?
Pharmacy labels in Germany, Australia, and Israel typically display total THC equivalent, derived from the HPLC figures on the original COA. The raw THCA figure will always be higher than the total THC equivalent because the 0.877 conversion factor accounts for molecular weight lost during decarboxylation. A batch showing 32% THCA converts to approximately 28.6% total THC equivalent under the standard formula.
Does the testing method (HPLC vs GC) affect which suppliers I can compare?
Yes. HPLC reports THCA before conversion; GC applies heat that converts THCA to THC during the test, so GC results look lower on THCA and higher on delta-9-THC. Comparing an HPLC-based COA from Supplier A with a GC-based COA from Supplier B without accounting for this difference will give you an inaccurate read on relative potency. Always confirm the method before drawing comparative conclusions.
What ISO accreditation should I require from a Canadian cannabis testing lab?
ISO/IEC 17025 is the international standard for testing and calibration laboratory competence. You should request that the issuing lab holds 17025 accreditation specifically scoped to cannabis cannabinoid potency by HPLC. The accreditation scope matters: a lab can be 17025-accredited for water testing but not for cannabis. Check the scope document, not just the certificate.
How many consecutive batch COAs should I request before signing a supply agreement?
A minimum of three consecutive batches of the specific cultivar is a practical starting point. Five or more gives you a more reliable picture of batch-to-batch consistency. Look for total THC equivalent variance of no more than 2-3 percentage points across batches. Higher variance suggests cultivation instability or inconsistent drying and curing protocols.
