How to Read a CBD Certificate (COA): What to Check Before Buying Hemp Oil
Certificate of analysis of CBD oil step by step: batch number, date of testing, laboratory accreditation, LOQ limit, and THC result. Check what this document confirms.
In four independent laboratory analyses of CBD products, the cannabidiol content deviated from the declaration on the label by 46 to 74 percent in the tested samples. The label is a promise from the manufacturer. The Certificate of Analysis is a record of measurement. It is the only document that allows you to verify this promise, but it does not solve anything on its own: what matters is whether it describes your batch, who issued it, and whether it provides numbers instead of the word “compliant”. The format of such a report is not standardized in any way, so two documents for the same type of product can look completely different. Below you have a step-by-step procedure for reading such a document, from the header to the contamination table, along with traps that are easiest to overlook.
KEY INFORMATION
• In a study of 202 CBD products, 74% deviated from the declaration by at least 10% (Gidal et al., Frontiers in Pharmacology, 2024).
• The batch number from the certificate must match the LOT number on the packaging; otherwise, the document describes a different product.
• The 0.3% THC threshold defines the industrial hemp plant and is not a limit for finished oil.
• The “ND” result without a stated LOQ does not carry any information.
Why is the label of hemp oil not enough?
Because four independent studies showed the same phenomenon in three markets. The percentage of samples that fell outside the tolerance of plus or minus 10 percent from the declaration was 69%, 50%, 46%, and 74%, respectively. The variation is large, and the direction is always the same.
The oldest of these studies covered 84 extracts purchased online: only 31% fell within the declared range, and THC was detected in 18 samples, up to 6.43 mg/ml (Bonn-Miller et al., JAMA, 2017). A Hungarian team searched 16 online stores in the local market and purchased 12 oils for testing: 6 fell within tolerance, five contained less cannabidiol than declared on the label, and one more (Vida et al., Frontiers in Pharmacology, 2023). The worst of them had 39 percent of the declared potency. This is a measurement of one national market, not the entire Union, although three of the sixteen stores had foreign addresses, and among the purchased brands were companies shipping goods all over Europe.
A study from Kentucky examined 80 products using the LC-MS/MS method: 37 of them, or 46%, deviated from the label by at least 10 percent, with 25 containing more CBD and 12 less (Johnson et al., Journal of Cannabis Research, 2022). The largest sample, 202 products from the open American market, showed 74% deviations from the declared potency. Additionally, 26% of products did not match the type stated on the packaging, i.e., the declaration of full spectrum, broad spectrum, or isolate (Gidal et al., Frontiers in Pharmacology, 2024). The differences between these types are explained in a separate post about types of CBD extracts.
What must be included in the header of the certificate?
Six fields: the name of the laboratory with the accreditation number, sample designation along with the batch number, date of sample receipt, date of report issuance, method name for each panel, and the signature of the person authorizing the result. A document without these fields is a printout of a table, not a report from the analysis.
| Field in the header | What to do with it |
|---|---|
| Batch number (LOT, Batch) | Compare character by character with the number on the packaging |
| Date of receipt and date of report | A report earlier than the production describes a different batch |
| Description of the sample matrix | Determines whether oil or raw extract was tested |
| Laboratory and accreditation number | Enter the number into the register of the accrediting body |
| Method for each panel | Lack of a method means the result is not reproducible |
| Limit of quantification (LOQ) | Without it, negative results mean nothing |
Pay attention to one more sentence that almost always appears in accredited reports: the results refer only to the tested sample. This is not a lawyer’s disclaimer but a description of reality. The laboratory tested a few milliliters sent by the client and does not comment on the rest of the batch at all.
What is the difference between a batch certificate and a raw material certificate?
A raw material certificate describes the extract or distillate purchased from the supplier before the manufacturer dilutes it with carrier oil. A batch certificate describes the contents of the bottle. The first document refers to an intermediate product, the second to what you actually consume, and one does not replace the other.
You can recognize them by two things. By the matrix: the report for raw material states “extract”, “distillate”, or “isolate”, while the report for the finished product states “oil”. By the order of magnitude of the result: distillate usually has several dozen percent CBD, while finished oil has a few. If the seller shows a document with a result of 82% CBD for an oil declared as 10%, it is not a discrepancy but a substituted document for a different subject.
This has practical consequences. The contamination panel performed on raw material does not include the carrier oil or the packaging process itself, so metals or residues from the carrier fat remain outside the examination. We have noticed while reviewing documents shared by sellers that the raw material certificate is often the only published report, and it is also the more impressive one because it shows a high percentage of purity. If you want to know how many substances are in your bottle, you need a report for its batch number.
How to read the cannabinoid panel and THC result?
Start with the units, not the number. The certificate usually provides mg/ml or mass percentage, while the label states milligrams for the entire package. Only after bringing both values to a common unit can you talk about compliance or discrepancy.
A 10 ml oil with a declaration of 1000 mg is 100 mg/ml. If the report shows 92 mg/ml, there are 920 mg in the bottle, which is 8 percent below the declaration, thus within the tolerance accepted in studies. A separate trap is percentages: the carrier oil weighs less than water, about 0.91 to 0.95 g/ml, so 10 percent by mass gives approximately 92 mg/ml, not 100. Hence, many apparent discrepancies.
The second thing is the acidic forms. In the raw plant, CBD mainly occurs as CBDA, and heating transforms it into the neutral form. Therefore, certificates provide total values: total CBD is CBD increased by 0.877 of the mass of CBDA, similarly for THC. High CBDA with low CBD means the product is raw, not defective.
Finally, THC. The 0.3 percent threshold, i.e., the sum of delta-9-THC and THCA calculated on the dry mass of the flower tops, rounded to one decimal place, defines the industrial hemp plant. It stands in Article 4 point 5 of the Act on Counteracting Drug Addiction (t.j. Dz.U. 2023 poz. 1939), as amended by the Act of March 24, 2022 (Dz.U. 2022 poz. 763) and effective from May 7, 2022. The finished oil is a different matrix, so relating this threshold to it leads nowhere. This has a practical effect when reading the certificate: the “total THC” position calculated with a coefficient of 0.877 does not correspond to the sum mentioned in the law. Read the THC result in mg/ml and multiply by the daily dose: that is the only number of practical significance, especially before a drug test.
What does ND mean, and what does a result below LOQ mean?
ND stands for “not detected”: the method saw nothing because the concentration was below the limit of detection. “Below LOQ” means something different: the substance is present, but in an amount that the method cannot reliably measure. The first record speaks of a lack of signal, the second of a signal that is too weak.
The limit of detection, marked as LOD, is the lowest distinguishable concentration from the noise of the equipment. The limit of quantification, or LOQ, lies higher and sets the threshold from which the result can be reported as a number. Both depend on the method, matrix, and sample preparation, so they differ between laboratories even for the same substance.
Hence the practical conclusion. The mere “ND” without a stated LOQ carries no information because it is unclear how low the laboratory could look. The same record with a limit of 0.5% and a limit of 0.001% describes two different products. Treat a “Pass” or “Compliant” result without a number the same way: you won’t find out whether the sample barely passed the limit or exceeded it by two orders of magnitude. With THC, there is one more thing: a result below LOQ is not the same as zero.
How to read the contamination panel in the certificate?
Read the numbers, not the verdicts, because detecting a substance and exceeding the limit are two different things. In the analysis of 202 CBD products, heavy metals were detected 52 times in 44 products, solvent residues 446 times in 181 products, and pesticides 55 times in 30 products.
The scale of exceedances was incomparably smaller: the regulatory limit was violated in 3% of metal determinations and 1% of solvent and pesticide determinations (Gidal et al., Frontiers in Pharmacology, 2024). This is the strongest argument for reading the values themselves. A document that instead provides the word “compliant” hides exactly that difference. Among metals, lead was the most frequently detected, and the highest concentrations among solvents reached hexane, xylenes, and methanol.
Solvents are assessed according to classes from the ICH Q3C guideline, not according to invented thresholds. Class one includes substances that should be avoided, such as benzene. Class two is limited quantitatively: methanol up to 3000 ppm, hexane up to 290 ppm. Class three collects solvents with low toxic potential, including ethanol and isopropanol, with a limit of 5000 ppm. These values in ppm are calculated by the guideline assuming 10 g of product per day, so they are cautious for oils dosed in drops. There is no standard stating “ethanol below 0.1 percent”, so citing such a threshold is a quote from marketing material. The microbiological panel, included with food products, should also provide values instead of just “not present”. What exactly is tested in these two panels and what is missing in them is detailed in a separate post about pesticides and microbiology in CBD products.
How to check if the laboratory really has accreditation?
Take the accreditation number from the header and enter it into the public register of the accrediting body. In Poland, it is maintained by the Polish Center for Accreditation, and abroad by DAkkS in Germany, UKAS in the UK, COFRAC in France, and A2LA in the United States.
The mere presence of an entry is only half of the verification. Accreditation according to the ISO/IEC 17025 standard always has a scope, published as an annex to the accreditation certificate, and lists specific methods along with matrices. A laboratory accredited for determining metals in water does not have to be accredited for determining cannabinoids in plant oil. Comparing the scope with the methods listed in the report takes a minute and clarifies more than the name of the unit itself.
What to avoid during this verification. The logo of the standard in the footer of the document is not proof of accreditation, as the graphic can be inserted arbitrarily. The declaration “tested in an independent laboratory” without a name and number is also not verifiable, and thus adds nothing. It also happens that the report comes from the manufacturer’s internal laboratory: this does not disqualify the result, but it removes the attribute of independence, which is what this whole procedure is about.
What to do if the seller does not have a certificate for your batch?
Email them to request the report for the LOT number from the packaging and see what comes back. No regulation requires publishing such documents for dietary supplements in Poland, so the lack of a certificate on the site does not determine anything by itself. What matters is the response to the request.
In the message, provide the batch number, purchase date, and product name, and ask for the full report in file form, not a screenshot of a table fragment. A good response includes a document with a batch number matching yours. A vague response, sending a raw material certificate or a report for a different batch is a signal to look for another seller. It also happens that the manufacturer simply tests less frequently than they produce, and that is also information.
The most convenient option is a QR code on the label leading directly to the report for that batch. Then the entire verification comes down to comparing the number on the screen with the number on the bottle. Before ordering anywhere, also review the general rules for safe purchases described in the post about where to buy CBD in Poland.
Frequently Asked Questions
What is a CBD oil Certificate of Analysis (COA)?
It is a report from the analysis of a single sample. It states who tested it, when, by what method, and with what limit of quantification, and then provides numerical results for cannabinoids and contaminants. It only refers to the sample received by the laboratory, so without a matching batch number, it says nothing about your bottle.
Does the 0.3% THC threshold apply to finished hemp oil?
No. The 0.3 percent threshold of the sum of delta-9-THC and THCA defines industrial hemp as a plant and refers to the dry mass of the flower tops. The finished oil is a different matrix, so on the certificate, look for the THC result given in mg/ml or in mass percentages and convert it to your daily dose.
What does an ND result mean on the analysis certificate?
ND stands for “not detected”, meaning the result is below the method’s limit of detection. It doesn’t say much on its own, as it all depends on the sensitivity of the test. Next to the result, there must be the limit of quantification (LOQ). An ND record with an LOQ of 0.5% and an LOQ of 0.001% describes two completely different products.
How to match the certificate to a specific bottle of oil?
Read the batch number from the packaging, labeled as LOT or Batch, and compare it character by character with the number in the report header. Also, check the dates: a document issued before the production of your batch describes a different batch. A QR code leading directly to the report shortens the verification to a few seconds.
How to check the laboratory’s accreditation from the certificate?
Enter the accreditation number into the public register of the accrediting body: the Polish Center for Accreditation in Poland or DAkkS, UKAS, COFRAC, and A2LA abroad. Check not only the existence of the entry but also whether the scope of accreditation covers the specific method and matrix. The logo of the standard in the footer is not proof.
How much can the CBD result differ from the label?
Cited studies accept a tolerance of plus or minus 10 percent of the declared value, and that is a reasonable point of reference. Before considering a discrepancy as a manufacturer’s error, convert the units: the report provides mg/ml or mass percentage, while the label states milligrams for the entire package. The carrier oil weighs less than water.
Certificates are easier to compare when you have several products in front of you, so start by reviewing the category of hemp oils and request a report for the batch of the one you choose.
This article is for informational and educational purposes. It contains internal links to product categories available in the store at Bucha. Prices and specifications may change: check the current data on the product page before purchasing.
Author: Michał Waluk · Published: 2026-05-29 · Updated: 2026-08-15
