How to Read a THCA COA (Certificate of Analysis)

COA Basics: What You Should See on Page 1

• Sample identifiers: batch/lot ID, sample ID, product name (strain), harvest date.
• Lab details: laboratory name, address, ISO/IEC 17025 accreditation status and certificate number, analyst signature, and report date.
• Methodology: instrument/method (e.g., HPLC for cannabinoids; HS-GC for residual solvents) and limits of detection/quantitation (LOD/LOQ).
• Measurement uncertainty: numeric value indicating the possible variation around reported results.
• Dry-weight basis: potency should be on a dry-weight basis; check moisture or water-activity notes.

Potency Panel: THCA, Δ9 THC, and Total THC

The potency section lists THCA, Δ9 THC, and other cannabinoids. To understand federal compliance and retail strength, confirm the Total THC calculation:

• Total THC formula: Total THC = (THCA × 0.877) + Δ9 THC.
• Dry-weight reporting: values should be calculated on a dry-weight basis (moisture removed).
• Batch match: the batch ID on the COA must match the goods you receive.

Tip: Compare the COA date to the harvest date. Fresh, properly cured flower should have realistic THCA and Δ9 THC values for the cultivar and grow method.

Compliance Check: Federal Δ9 THC Threshold

At the federal level, hemp is defined by Δ9 THC ≤ 0.3% by dry weight. Confirm that the reported Δ9 THC meets this threshold, and that the test conditions are clearly documented (dry-weight basis, moisture/aw control).

Remember: States can set additional rules. Always verify your state’s requirements.

Safety Panels: What Clean COAs Include

• Residual solvents (where applicable): report via HS-GC/GC-MS and benchmark against USP <467> / ICH classes (Class 1, 2, 3).
• Pesticides & heavy metals: screening for common agricultural residues (e.g., myclobutanil) and metals (As, Cd, Pb, Hg).
• Microbial testing: pathogenic bacteria (e.g., Salmonella, STEC), total yeast & mold, and sometimes Aspergillus species by state rule.
• Mycotoxins: aflatoxins, ochratoxin A per state or method performance requirements.
• Water activity (a_w): acceptable range for dried flower is typically 0.55–0.65 to support shelf stability and safety.

If any of these panels are missing for flower, request full testing or choose another lot.

Terpenes (Optional but Useful)

Some labs include a terpene profile. While not a compliance requirement in many jurisdictions, terpene data helps differentiate strains and guide merchandising (e.g., limonene-forward vs. myrcene-forward lots).

How to Vet the Lab

• Accreditation: confirm ISO/IEC 17025 accreditation is current and covers the reported methods.
• Proficiency testing: look for participation in interlaboratory programs (e.g., NIST CannaQAP) to improve comparability and detect bias.
• Method transparency: the COA should specify instruments, methods, LOD/LOQ, and uncertainty.

If you cannot verify accreditation or scope, treat the report as a red flag.

Common Red Flags

• COA lacks batch/lot ID or it does not match packaging.
• No method, LOD/LOQ, uncertainty, or analyst signature listed.
• Unrealistic round numbers (e.g., “30.00%” across many samples) without uncertainty.
• Δ9 THC not reported separately from THCA; only “Total THC” shown.
• Missing entire safety panels for flower (residual solvents, microbials, pesticides, heavy metals).

Step-by-Step COA Review Checklist

1. Confirm batch/lot ID, product name, harvest date, and report date.
2. Verify the lab’s ISO/IEC 17025 accreditation and that methods are within scope.
3. Check dry-weight basis and note moisture or a_w values.
4. Recalculate Total THC = (THCA × 0.877) + Δ9 THC and confirm Δ9 THC ≤ 0.3% (federal threshold).
5. Review safety panels: residual solvents, pesticides, heavy metals, microbials, mycotoxins.
6. Look for LOD/LOQ, measurement uncertainty, and analyst signature.
7. Save the COA PDF with the shipment for audit trail and future restocks.

Next Steps

If you’re evaluating a new lot, compare the COA to your target specs and state rules, then align the purchase with your program:

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FAQs

What does “dry-weight basis” mean on a COA?

It means potency is calculated after removing moisture from the sample, ensuring comparable results across batches and labs.

How do I calculate Total THC?

Use (THCA × 0.877) + Δ9 THC. The 0.877 factor accounts for decarboxylation from THCA to THC.

Do all COAs include residual solvent testing?

Flower should be tested for solvents if extraction or processing occurred; concentrates must include it. Results are typically benchmarked against USP <467>.

What is ISO/IEC 17025 and why does it matter?

It’s the international standard for testing lab competence. Accreditation builds confidence that methods are validated and results are reliable.

What water activity is acceptable for dried flower?

A typical acceptable range is 0.55–0.65 a_w for dried cannabis flower.