Buying a cannabis concentrate involves more than comparing the product name, advertised potency or appearance. For consumers researching concentrate products, a Certificate of Analysis (COA) can provide laboratory information about a particular sample or batch.
A COA may show cannabinoid concentrations, testing methods, batch information and results for various contaminants. Understanding how to read those results can make it easier to compare product information with the laboratory documentation provided.
This Sluggers Carts UK THC concentrate COA guide explains what to look for on a laboratory report, how to interpret the main sections and which details deserve closer attention before making a purchasing decision.
What Is a THC Concentrate COA?
A THC concentrate COA, or Certificate of Analysis, is a laboratory report containing analytical results for a tested cannabis concentrate or related product.
Depending on the laboratory and product, a COA can contain information about:
- Cannabinoid concentrations
- THC and THCA
- CBD and other cannabinoids
- Terpene content
- Residual solvents
- Heavy metals
- Pesticides
- Microbial contaminants
- Sample identification
- Batch or lot number
- Testing date
- Laboratory information
- Analytical methods
The exact sections vary between laboratories and products.
For a broader explanation of concentrates, start with our THC Concentrates Guide, which covers concentrate types, potency and product characteristics.
Why Should You Check a THC Concentrate COA?
A product description tells you what the seller says about a product.
A COA provides laboratory results for the sample that was tested.
Those are two different things.
For example, a concentrate might be advertised as containing a particular cannabinoid profile. The corresponding laboratory report can allow a buyer to compare that description with the reported analytical results.
A COA can therefore help you examine:
- Whether the report identifies the product or batch
- What cannabinoids were detected
- The reported cannabinoid concentrations
- Whether contaminant testing was performed
- Which laboratory performed the analysis
- When the sample was tested
- Which analytical methods were used
However, a COA should not be interpreted as a blanket guarantee of product quality, safety or UK legality.
How to Read a THC Concentrate COA Step by Step
When reviewing a COA, don’t focus only on the biggest THC number.
Instead, work through the document systematically.
1. Check the Product Name
Start at the top of the report.
Look for a product name, sample name or sample identification that corresponds with the concentrate you are researching.
For example, the report might identify the material by:
- Product name
- Strain or cultivar
- Extract type
- Sample ID
- Batch number
- Lot number
The terminology can differ between laboratories.
The important question is whether the report can reasonably be connected to the product being evaluated.
2. Find the Batch or Lot Number
Batch information is one of the most useful details on a COA.
A laboratory report should ideally provide a way to connect the analytical result to the specific material tested.
Look for:
Batch number
Lot number
Sample ID
or another unique identifier.
Then compare it with the batch information supplied for the product.
A laboratory result from one batch should not automatically be treated as proof of the composition of a different batch.
3. Check the Testing Date
Find the date the sample was received, tested or reported.
Laboratory reports can contain several dates, so don’t assume that every date shown means the same thing.
You may see:
- Sample received date
- Testing date
- Report date
- Analysis date
The report should make clear which date relates to the laboratory analysis.
A current product paired with an unrelated or very old report deserves additional scrutiny.
4. Identify the Laboratory
Look for the laboratory’s:
- Name
- Address
- Contact information
- Accreditation information where provided
- Report number
- Laboratory certification or credentials
The laboratory section is important because it identifies who performed the analysis.
For certain UK regulatory contexts, the Home Office discusses analytical testing and states that, for its particular exemption assessment, relevant laboratories should be accredited to ISO/IEC 17025 by a relevant accrediting body, with UKAS identified for UK laboratories.
That does not mean every consumer cannabis COA is automatically a legal document simply because a laboratory logo appears on it.
Always consider what was tested, which method was used and what the report actually establishes.
5. Read the Cannabinoid Profile
The cannabinoid section is usually one of the first places buyers look.
A report may list cannabinoids such as:
- Δ9-THC
- THCA
- CBD
- CBDA
- CBG
- CBGA
- CBC
- CBN
- THCV
- Other cannabinoids
Not every COA will contain every cannabinoid.
The analytical method determines which compounds the laboratory tested for and how sensitive the test was.
THC vs THCA on a COA
One of the most important distinctions is between THC and THCA.
THCA is an acidic cannabinoid precursor associated with THC. The Home Office notes that THCA can readily degrade to THC through heat or other changes.
This means you should not automatically treat a THCA percentage and a measured THC percentage as interchangeable.
Look at exactly how the laboratory presents the results.
6. Understand Total THC
Some laboratory reports include a calculated Total THC figure.
This can involve a calculation incorporating THC and THCA.
A commonly used calculation in cannabis testing is based on the potential conversion of THCA into THC, although the precise calculation and reporting convention can vary.
Therefore, don’t assume that every laboratory’s “Total THC” field is calculated identically.
Instead, look for:
- THC result
- THCA result
- Total THC result
- Calculation or notes
- Units of measurement
If the calculation is unclear, the laboratory’s methodology or reporting notes are more useful than guessing from the headline number.
7. Check the Units
COAs can use different units.
You might encounter:
- %
- mg/g
- mg per serving
- mg per container
- ppm
- ppb
For cannabinoid concentration, percentages are common.
For contaminants, much smaller units may be used.
Don’t compare two results until you know they are expressed using the same units.
For example:
10%
and
100 mg/g
may represent the same concentration, depending on the substance and calculation.
Understanding the unit prevents simple numerical comparisons from becoming misleading.
8. Look at Terpene Results
Some concentrate COAs include terpene testing.
Terpenes are aromatic compounds associated with cannabis and many other plants.
A terpene section may identify compounds such as:
- Myrcene
- Limonene
- Caryophyllene
- Linalool
- Pinene
- Humulene
The report may show individual terpene concentrations and sometimes a total terpene percentage.
For buyers comparing concentrates, terpene information can provide additional product information beyond cannabinoid percentages.
If you’re comparing extract types, our Liquid Diamonds and Live Resin Vape Guide can help explain how different concentrate and vape formulations are described.
9. Check Residual Solvent Testing
Depending on how an extract was produced, solvent testing can be relevant.
A residual-solvent panel may look for compounds associated with extraction or processing.
A COA may show:
- Solvent name
- Result
- Detection limit
- Reporting limit
- Pass/fail designation
- Maximum permitted or reference limit
Don’t simply look for the word “Pass.”
Look at what was actually tested and the numerical results where available.
10. Review Heavy Metal Testing
Heavy-metal testing can identify metals that may be relevant to cannabis products.
A laboratory panel may include substances such as:
- Lead
- Arsenic
- Cadmium
- Mercury
Again, check the actual result and units.
A result such as ND does not necessarily mean that absolutely zero of the substance exists.
It generally means that the substance was not detected at or above the laboratory’s reporting or detection threshold.
That distinction matters when interpreting a COA.
11. Check Pesticide Testing
Some COAs include pesticide panels.
Depending on the testing program, dozens of compounds may potentially be screened.
Look for:
- Pesticide name
- Result
- Detection limit
- Reporting limit
- Applicable reference limit
- Pass/fail interpretation
A comprehensive report will make the scope of the testing clear.
12. Understand “ND” on a COA
ND commonly means Not Detected.
It does not necessarily mean the laboratory proved that absolutely none of the substance exists.
Instead, the result generally means the substance was not detected at or above the laboratory’s relevant reporting or detection threshold.
This is why the detection limit matters.
For example:
Analyte: Substance X
Result: ND
LOD: 0.01 ppm
The meaningful interpretation is that the laboratory did not detect Substance X at or above the stated detection capability.
Government guidance concerning controlled cannabinoids also highlights the importance of analytical sensitivity when demonstrating compliance with specified limits.
13. Check the LOD and LOQ
Two technical terms you may see are:
LOD — Limit of Detection
and
LOQ — Limit of Quantification
The LOD generally refers to the lowest level at which the laboratory can reliably detect the analyte under the specified method.
The LOQ concerns the level at which the analyte can be quantitatively measured with the method.
These values are particularly important when reviewing very low concentrations.
A result of “ND” should therefore be interpreted alongside the laboratory’s detection or reporting limits.
14. Look for a Pass/Fail Interpretation
Some laboratories provide an easy-to-read:
PASS
or
FAIL
designation.
This can be useful, but don’t stop there.
Find out:
- What standard was applied?
- Which compounds were tested?
- What limits were used?
- Was the result calculated against a particular regulatory standard?
- Does the standard actually apply to the product and jurisdiction?
A “PASS” statement on a COA does not automatically mean the product is legal to sell or possess in the UK.
A laboratory test and a legal determination are different things.
15. Check Whether the COA Matches the Product
This is one of the most important buyer checks.
Compare:
Product name
Batch number
Lot number
Sample ID
Testing date
and any other identifying information.
If the product you’re considering has one batch number and the COA identifies another, don’t automatically assume the laboratory report represents the product you’re looking at.
This is particularly important when a website displays one laboratory report across multiple products or batches.
Common THC Concentrate COA Red Flags
A COA deserves closer examination if you encounter:
No batch information
If you cannot connect the laboratory report to a particular product or batch, its usefulness for evaluating that product is limited.
No laboratory identification
A report without clear laboratory information provides less transparency.
Only a THC percentage
A single potency number provides much less information than a report showing cannabinoid and contaminant testing.
Missing testing methodology
If the document gives results but little information about the analytical method, investigate further.
Extremely old report
A report may not represent the current production batch.
Product and COA names don’t match
A mismatch should be clarified before assuming the report belongs to the product.
Suspiciously generic documentation
A generic laboratory report that appears to be used for numerous unrelated products deserves additional scrutiny.
No contaminant testing
A potency result alone doesn’t tell you what other substances were or weren’t tested.
COA vs Product Description: What’s the Difference?
A product description is marketing and product information supplied by the seller.
A COA is laboratory documentation containing analytical results.
They can complement each other.
For example:
Product description:
“Live resin concentrate with a particular cannabinoid profile.”
COA:
Laboratory results showing cannabinoids and other tested parameters for a specified sample or batch.
The buyer can then compare the product information with the available laboratory documentation.
This is why COAs are useful as part of a broader purchasing assessment.
Can a COA Prove a THC Concentrate Is Legal in the UK?
No.
A COA is not a legal certificate.
UK controlled-drug legislation is separate from laboratory testing.
The Home Office states that cannabis is a Class B controlled drug and that THC and certain other cannabinoids are controlled under the Misuse of Drugs Act 1971 and related regulations. Specific exemptions and licensing arrangements can apply depending on the product and circumstances.
The Home Office also explains that certain exempt-product requirements involve specific analytical considerations and limits.
Therefore:
COA = laboratory information
UK law = legal status
Don’t treat one as a substitute for the other.
For more information, read our UK Cannabis Laws Guide and our dedicated THCA Diamonds Guide when evaluating different concentrate-related product categories.
How to Compare Two THC Concentrate COAs
If you’re comparing two concentrates, create a simple checklist.
| COA category | Product A | Product B |
|---|---|---|
| Product identification | Check | Check |
| Batch number | Check | Check |
| Testing date | Check | Check |
| Laboratory | Check | Check |
| THC | Check | Check |
| THCA | Check | Check |
| Other cannabinoids | Check | Check |
| Terpenes | Check | Check |
| Residual solvents | Check | Check |
| Heavy metals | Check | Check |
| Pesticides | Check | Check |
| Microbial testing | Check | Check |
| Detection limits | Check | Check |
| Testing method | Check | Check |
This approach is more informative than comparing THC percentages alone.
COA Checklist for UK Concentrate Buyers
Before relying on a COA, check:
1. Product identity
Does the report clearly identify the product or sample?
2. Batch information
Can you connect it to the batch being sold?
3. Laboratory
Is the testing laboratory clearly identified?
4. Testing date
When was the sample analyzed?
5. Cannabinoids
What cannabinoids were actually tested?
6. THC and THCA
Are the individual results clearly reported?
7. Contaminants
Were relevant contaminant panels performed?
8. Units
Are you interpreting the numbers using the correct units?
9. Detection limits
What do “ND” results actually mean?
10. Methodology
Does the report explain how the testing was performed?
11. Consistency
Does the COA agree with the product information?
12. Legal status
Have you separately checked whether the product is lawful in the UK?
How COAs Fit Into Choosing a THC Concentrate
A COA should be treated as one part of your product-evaluation process.
Other factors can include:
- Product description
- Ingredients
- Cannabinoid profile
- Extract type
- Batch information
- Manufacturing information
- Laboratory documentation
- Hardware, where applicable
- Packaging information
- Storage requirements
- Applicable UK regulations
For buyers researching different concentrate types, our THC Concentrates Guide is the main resource to explore before comparing individual formats.
You can also learn about specific concentrate categories through our related educational content on Live Badder and THCA Diamonds.
Frequently Asked Questions
What does COA mean in cannabis?
COA stands for Certificate of Analysis. It is a laboratory report containing analytical results for a tested sample or batch.
What should I look for on a THC concentrate COA?
Start with product identification, batch information, laboratory details, testing date, cannabinoid results, contaminant testing, units, detection limits and analytical methods.
Does a COA prove a concentrate is safe?
No. A COA documents particular laboratory tests and results. It should not be interpreted as an absolute guarantee of safety or quality.
Does a higher THC percentage mean a better concentrate?
No. THC percentage is only one measurement. Other factors include cannabinoid profile, terpene information, extraction characteristics, testing scope and product documentation.
What does ND mean on a COA?
ND generally means Not Detected at or above the laboratory’s applicable detection or reporting threshold. Check the report’s LOD or LOQ to understand the result.
How important is the batch number?
Very important. It helps connect the laboratory results to a specific product batch or sample.
Can I trust a COA without a batch number?
Use caution. Without a clear connection between the report and the product being sold, it becomes harder to establish that the laboratory result represents that particular product.
Does a COA make THC concentrates legal in the UK?
No. A COA is laboratory documentation, not a legal authorization. UK controlled-drug law applies separately.
Should I compare COAs instead of THC percentages?
Comparing the broader testing information can provide more useful context than comparing THC percentages alone.
Final Thoughts: Read the Whole COA, Not Just the THC Number
A THC concentrate COA can contain considerably more information than a headline potency figure.
When reviewing a laboratory report, check the product identification, batch number, testing date, laboratory, cannabinoid profile, contaminant panels, units, detection limits and testing methodology.
Most importantly, compare the COA with the product information and remember that laboratory testing does not independently determine UK legal status.
For more concentrate education, start with our THC Concentrates Guide, then explore the relevant guides for specific concentrate formats.
The better you understand a COA, the easier it becomes to ask informed questions about the laboratory documentation behind a cannabis concentrate rather than relying solely on marketing claims.