How to Read a Semaglutide Certificate of Analysis: A Plain-English Guide

What Is a Certificate of Analysis?

A certificate of analysis is a document from a testing laboratory that reports the results of quality testing on a specific batch of medication. For compounded semaglutide, the COA tells you whether the product in your vial is actually semaglutide, how pure it is, whether it is the right strength, and whether it is sterile.

Think of it like a nutrition label for pharmaceuticals, except instead of calories and fat grams, you are looking at purity percentages and bacterial contamination results.

Every batch of compounded semaglutide should have a COA. A batch is a specific production run from the pharmacy, identified by a lot number. Your vial should have a lot number on the label, and that number should match the batch number on the COA.

FormBlends publishes COAs for every batch on its website and can provide them to any patient who requests their specific batch report. This should be the standard in the industry. Unfortunately, many providers either do not test their products, test internally without independent verification, or simply refuse to share results with patients.

The 5 Sections of a COA, Explained in Plain English

1. Identity confirmation

This section confirms that the sample is actually semaglutide. Testing methods include mass spectrometry or HPLC peak matching against a reference standard. The result should say something like "Identity confirmed" or "Conforms to reference standard."

What you are looking for: Confirmation that the product is semaglutide base form (not a salt form). If the identity section lists "semaglutide sodium" or "semaglutide acetate," that is a concern. The clinical trials used the base form.

2. Purity (HPLC)

HPLC stands for high-performance liquid chromatography. It separates the components of the sample and measures what percentage is the target molecule (semaglutide) versus impurities.

What the numbers mean:

• Above 98%: High-quality result. This is what you want to see.
• 95-98%: Acceptable. The remaining percentage is related impurities or degradation products.
• Below 95%: A concern. Higher impurity levels may indicate poor quality raw material, improper storage, or contamination during compounding.
• Below 90%: Do not use this product.

3. Potency (assay)

Potency measures the actual concentration of semaglutide in the solution compared to the labeled concentration. If your vial says "5mg/mL," the potency test tells you how close the real concentration is to that number.

What the numbers mean:

• 90-110% of label claim: Acceptable range per USP standards. A 5mg/mL vial testing at 4.5-5.5mg/mL is within spec.
• Outside 90-110%: The medication is either underdosed (you are getting less than prescribed) or overdosed (you are getting more). Either is a problem. Underdosing reduces effectiveness. Overdosing increases side effect risk.

Why this matters practically: If your vial is labeled 5mg/mL but actually contains 3.5mg/mL, your intended 1.0mg dose is really only 0.7mg. You would see weaker appetite suppression and wonder why the medication is not working.

4. Endotoxin testing (BET)

Bacterial endotoxins are toxins released by certain bacteria. They can cause fever, inflammation, and in severe cases, septic shock when injected. The bacterial endotoxin test (BET), also called the LAL test (limulus amebocyte lysate), measures endotoxin levels.

What the numbers mean:

• Below USP limits (typically <5 EU/mL for injectable products): Pass. The product is within safe limits for injection.
• Above USP limits: Fail. The product should not be injected.

This test result is non-negotiable. If the COA does not include endotoxin testing, or if the result exceeds USP limits, do not use the product.

5. Sterility testing

Sterility testing checks whether the product contains viable microorganisms (bacteria, fungi). For an injectable product, sterility is critical.

What the result should say: "No growth observed" or "Conforms to USP sterility requirements" after the standard 14-day incubation period.

What a failure looks like: "Growth observed" or any indication of microbial contamination. A non-sterile injectable product can cause infections ranging from localized reactions to systemic sepsis.

Red Flags on a COA

• Missing tests. A complete COA should include all five sections above. If endotoxin or sterility testing is missing, the pharmacy may be skipping these tests to save money.
• No lab name. The COA should identify the testing laboratory. If there is no lab name, you cannot verify the results independently.
• Internal testing only. A COA from the pharmacy's own lab is less reliable than one from an independent third-party lab. See the next section.
• Batch number mismatch. The batch/lot number on the COA should match the lot number on your vial label. If they do not match, the COA is not for your product.
• Old dates. Testing should be recent. If the COA is dated many months before your vial was shipped, the medication may have degraded since testing. Semaglutide has a finite shelf life, particularly once reconstituted.
• Salt form identification. If the identity section shows semaglutide sodium, semaglutide acetate, or any salt form, the product is not the base form used in clinical trials.

Why Third-Party Testing Matters

There is a meaningful difference between a pharmacy testing its own product and sending that product to an independent laboratory for verification.

Internal testing means the pharmacy performed the tests in its own lab. The results may be accurate, but there is an inherent conflict of interest: the pharmacy has a financial incentive for the product to pass.

Third-party testing means an independent, accredited laboratory performed the tests. The lab has no financial relationship with the pharmacy and no incentive for the product to pass or fail. This independence is what makes the results trustworthy.

Look for the name of the testing laboratory on the COA. You should be able to look up the lab and verify that it is accredited (ISO 17025 or equivalent). FormBlends uses independent third-party testing for every batch and names the laboratory on every COA.

How to Get a COA From Your Provider

1. Find the lot number on your semaglutide vial label.
2. Contact your provider's customer support and ask: "Can I get the certificate of analysis for batch [lot number]?"
3. If they provide it, review it using the guide above.
4. If they refuse, cannot produce it, or say they do not have one, that is a strong signal to switch providers. A provider that cannot verify the quality of what they ship is asking you to inject something on trust alone.

Some providers publish COAs proactively on their website or include them with shipments. This is the gold standard. If your provider does this, you are in good hands on the quality transparency front.

Frequently Asked Questions