How to Read a Certificate of Analysis (COA)

What is a Certificate of Analysis?

A Certificate of Analysis (COA) is a document issued by an accredited laboratory that shows the results of tests performed on a product. For botanical products, a COA verifies purity, potency, and safety.

Think of a COA as a product's report card. It tells you exactly what's in the product and confirms it meets safety standards. Reputable vendors provide COAs for every batch they sell, and you should always review them before purchasing.

Key Sections of a COA

While COAs can vary in format between laboratories, most include these essential sections:

1. Laboratory Information

• Lab Name and Address: The testing facility's identifying information
• Accreditations: Look for ISO 17025 or similar certifications
• Contact Information: Legitimate labs provide ways to verify results

2. Sample Information

• Sample ID/Batch Number: Unique identifier for the tested batch
• Sample Description: What product was tested
• Date Received: When the lab received the sample
• Date Tested: When testing was performed

3. Test Results

This is the most important section. For botanical products, look for:

Potency Testing
Shows the concentration of active compounds, given as a percentage of the total extract. Look for the total active-compound content. Results should be expressed as percentages or mg/g.

4. Contaminant Testing

This section confirms the product is free from harmful substances:

• Heavy Metals: Lead, arsenic, mercury, cadmium (should all be below detection limits or within safe thresholds)
• Microbial Testing: Bacteria counts, E. coli, Salmonella (should show "Not Detected" or "Pass")
• Pesticides: Tests for common agricultural chemicals
• Mycotoxins: Tests for mold-produced toxins

Red Flags to Watch For

Be cautious if a COA is missing contaminant testing, shows results that exceed safe limits, lacks a batch number, or can't be verified with the laboratory directly. Also be wary of COAs that are clearly altered or have inconsistent formatting.

Understanding Test Results

Here's how to interpret common result formats:

Pass/Fail Results

Some tests (especially microbial) show simple pass/fail results. "Pass" or "Compliant" means the product meets safety standards. "Fail" or "Non-Compliant" means it doesn't - avoid these products.

Numerical Results

Many results show specific numbers with units:

• Parts per million (ppm) or ppb: Used for contaminants
• mg/g: Milligrams per gram, another way to express concentration
• CFU/g: Colony forming units per gram, used for microbial counts

Detection Limits

"ND" or "Not Detected" means the substance wasn't found at levels the test can measure. "< LOQ" means below the Limit of Quantification - present but too low to measure precisely. These results typically indicate a clean product.

Verifying a COA

Don't just trust that a COA is legitimate. Here's how to verify:

1. Check the Lab: Google the laboratory name. Is it a real, accredited testing facility?
2. Match Batch Numbers: Does the COA batch number match your product's label?
3. Contact the Lab: Reputable labs can confirm they tested a specific sample
4. Review the Date: Is the COA recent? Testing should be from the current batch
5. Look for Completeness: Quality COAs include all relevant tests, not just potency

COA Quick Checklist

• Lab is accredited (ISO 17025 or equivalent)
• Batch number matches product label
• Test date is recent (within 6-12 months)
• Potency testing is included
• Heavy metals testing shows safe levels
• Microbial testing shows "Pass" or "Not Detected"
• No signs of alteration or editing
• Lab contact information is verifiable

Why COAs Matter

Requesting and reviewing COAs protects you in several ways:

• Safety: Confirms products are free from harmful contaminants
• Accuracy: Verifies you're getting what's advertised
• Consistency: Helps you compare products and find reliable options
• Accountability: Vendors who provide COAs stand behind their products

What Each Test Actually Answers

A COA is a stack of separate questions, each answered by a different instrument. Knowing which instrument produced a number tells you what the number can and cannot prove. A clean heavy-metals line says nothing about potency, and a strong potency line says nothing about mold. The table lists the tests you will meet most often on a botanical COA, the method a lab usually uses for each, and the one question each result answers.

Test	Method usually used	The question it answers	What it cannot tell you
Potency of named compounds	High-performance liquid chromatography (HPLC)	How much of each compound the lab looked for is in the sample	Whether compounds the lab did not look for are present
Heavy metals	Inductively coupled plasma mass spectrometry (ICP-MS)	How much lead, arsenic, cadmium and mercury is in the sample	Anything about organic contaminants
Residual solvents	Headspace gas chromatography (GC)	Whether solvent from extraction is still in the finished product	Whether the solvents tested are the ones that were actually used
Pesticide residues	Liquid or gas chromatography with mass spectrometry	Whether the listed agricultural chemicals are present above the reporting limit	Any pesticide that is not on the lab's list
Microbial counts	Plate counts and organism-specific tests	Whether total bacteria, yeast, mold, and named organisms were found in the portion tested	Whether every unit in the batch is the same as the portion tested
Mycotoxins	Liquid chromatography with mass spectrometry	Whether the toxins the lab listed are present	Whether the product is mold-free in general
Moisture or loss on drying	Oven drying or a moisture analyser	How much of the sample's weight was water	Anything about safety on its own

Notice the right-hand column. Every test is limited to what the lab was asked to look for. A COA with six clean lines is a good start, and a COA with the right six lines for this kind of product is better.

Units: Reading the Numbers Without Guessing

Different sections of one COA often use different units, which is where most confusion starts. The conversions are plain arithmetic, so it is worth keeping them in front of you while you read.

Unit as written	Says the same thing as	Where you see it
1 percent (%)	10 mg per gram, or 10,000 ppm	Potency
1 mg/g	0.1 percent, or 1,000 ppm	Potency
1 ppm (parts per million)	1 mg per kilogram, or 1 microgram per gram	Heavy metals, solvents, pesticides
1 ppb (parts per billion)	0.001 ppm, or 1 microgram per kilogram	Mycotoxins, some pesticides
CFU/g (colony-forming units per gram)	A count of living organisms that grew on a plate, per gram of sample	Microbial counts
ND or <LOQ	Not detected, or detected but below the level the lab can measure reliably	Every contaminant section

Turning a potency percentage into milligrams

Suppose a COA reports a named compound at 4.2 percent in an extract. That is 42 mg of the compound in every gram of extract. If the label says a serving is 250 mg of extract, one serving holds 250 times 0.042, which is 10.5 mg of that compound. If you take two servings a day, the daily amount is 21 mg. Doing this once puts the COA and the label in the same unit, and it shows you at once when the two do not agree.

As received or dry weight?

Some COAs report results on an "as received" basis, meaning the sample as the lab got it, water included. Others report on a "dry weight" basis, with the water corrected out. A sample that holds 8 percent moisture and reports 4.2 percent of a compound as received would report about 4.6 percent on a dry basis (4.2 divided by 0.92). Neither is wrong. They are simply not comparable to each other, so check which basis each COA uses before comparing two products.

A Worked Example: Reading One COA Line by Line

The values below are invented to show the process; they are not from any real product. Read the table as if it were pasted from a lab report, and ask of each row what you would want to know before you were satisfied.

Line on the report	Reported	What to check	Verdict in this example
Batch or lot number	L-2217	Does it match the number printed on your bottle?	Yes, so this report belongs to this product
Date tested	Reported six weeks before the bottling date	Was the sample taken from the finished lot?	Ask the vendor; testing before bottling may be fine, but they should say so
Accreditation	ISO/IEC 17025 listed	Does the lab's scope cover these methods?	Look up the lab; accreditation is for specific tests, not the whole lab
Potency	4.2 percent of the named compound	Does the label claim agree after the arithmetic above?	Label says 10 mg per serving; the report gives 10.5. Agrees
Lead	ND	What was the detection limit for the instrument?	Not enough information if the limit is missing
Residual solvents	Not tested	Was a solvent used to make the product?	If it was an ethanol extract, ask why this line is blank
Total yeast and mold	Under 100 CFU/g	What was the limit the lab compared it with?	Only meaningful if the report states the limit
Signature and date	Present	Can the lab confirm the report if asked?	Yes, if a contact or verification code is printed

The example product comes out with two good lines and several open questions. That is a typical outcome. A COA is rarely a clean pass or a clear fail; it is a set of questions you can put to the seller, and how they answer is part of the evidence.

Red Flags and What They Usually Mean

What you see	Why it matters	What to do
No batch number, or one that does not match your bottle	The report may describe a different product	Ask for the report that matches your lot
The seller's name is on the report but no lab is	The seller may have written it themselves	Ask for the original from the laboratory
Round or identical numbers across batches	Real measurements vary a little from batch to batch	Compare two reports side by side and ask about any that match exactly
Only potency is tested	Safety lines are missing	Ask whether contaminant tests were done and request them
Results shown as "Pass" with no numbers	You cannot see how close to the limit it was	Ask for the numeric values and the limits used
A report that is a screenshot with edited fonts or misaligned text	May have been altered	Ask the lab to confirm it directly
Report is more than a year old, or from before a recipe change	The current product may differ	Ask for a current report

What a COA Cannot Do

Even a good COA has limits, and it helps to hold them in mind so the document is neither dismissed nor over-trusted.

• It describes a sample, not every bottle. The lab tests a small portion drawn from a batch. If a batch is not well mixed, the portion tested may not match every unit filled from it.
• It describes one moment. A report dated before bottling says nothing about what happened to the product afterward, including storage and heat.
• It covers only the list of tests. A contaminant that was not on the list is not on the report, and its absence from the report is not evidence it was absent from the product.
• It depends on the lab. Two labs can report different numbers for the same sample, especially for potency. Look at who did the testing and whether the methods are named.
• It is not a recommendation. A product can pass every line and still be wrong for you, your medications or your situation. See the guide on responsible dosing for how to start.

Questions to Ask the Seller

1. Can I see the report for the lot number printed on this bottle?
2. Which laboratory produced it, and may I contact them to confirm it?
3. Were the contaminant tests run on the finished product or on the raw material?
4. What limits were the results compared against, and where do they come from?
5. How often do you test, and does every batch get its own report?

A seller who welcomes these questions and answers them plainly is telling you something. One who avoids them is telling you something as well.

Conclusion

Learning to read COAs is one of the most valuable skills for any botanical consumer. It takes just a few minutes to review a COA, but that small investment of time can protect your health and ensure you're getting quality products.

Always ask for COAs before purchasing botanical products. If a vendor can't or won't provide current lab testing, consider that a red flag and look elsewhere.

Our Transparency Promise
Pure Extracts provides comprehensive COAs for every batch of every product. We believe you deserve full transparency about what you're consuming. Our lab results are always available upon request and include complete potency and safety testing.