Telehealth programs have learned that "third-party tested" reassures people, and a certificate of analysis is the document they point to. It is a useful document. It is also narrower than the marketing suggests. This page reads one from top to bottom.
What a COA is
A certificate of analysis is a report from a laboratory stating that a specific lot of material was tested against a specific set of acceptance criteria on a specific date, with the results. For a compounded sterile injectable, the lot is one batch made by the pharmacy or outsourcing facility. For a bulk active pharmaceutical ingredient, the lot is one batch of powder from the API manufacturer. Both are called COAs. Only the first tells you about what is in your vial.
Reading it section by section
Header
- Product name and strength. Should match your dispensed label exactly: active ingredient, concentration in mg per mL, volume.
- Lot or batch number. Must match the lot on your vial. If your vial has no lot number, that is the first problem.
- Manufacture date and beyond-use date. For compounded sterile preparations the beyond-use date is set by USP 797 rules and any stability study the compounder has; it is usually weeks, not years.
- Testing laboratory. Name and address. An in-house result is not wrong, but an independent laboratory is what "third-party tested" is supposed to mean. You can look the lab up.
Tests
For a sterile injectable peptide such as semaglutide or tirzepatide, the tests you should expect to see, with the reference method where one exists:
| Test | What it answers | Reference |
|---|---|---|
| Identity | Is the active ingredient what the label says? Usually HPLC retention time or mass spectrometry against a standard. | USP monograph methods where one exists; validated in-house methods otherwise |
| Assay (potency) | How much active ingredient is present, as a percentage of label claim, with an acceptance range printed next to it | Validated HPLC method |
| Sterility | Does the lot contain viable microorganisms? Reported as pass or fail after incubation | USP chapter 71 |
| Bacterial endotoxins | Pyrogen content, reported in endotoxin units per mL or per dose against a limit | USP chapter 85 |
| pH | Is the solution in the range the formulation was designed for? | USP chapter 791 |
| Particulate matter | Visible or sub-visible particles in an injectable | USP chapters 788 and 790 |
| Related substances or impurities | Degradation products and, for peptides, related sequences | Method-specific; often reported as total impurities percent |
A COA that lists identity and assay only is a partial picture. Sterility and endotoxin results are what distinguish an injectable from a bench chemical.
Results and specifications
Each test should show three things side by side: the specification (the acceptance range), the result, and a pass or fail. A result without a specification is a number you cannot interpret. "Conforms" without a number is a conclusion you cannot check.
Sign-off
A name, a title and a date from the laboratory. Unsigned, undated documents are drafts.
Matching the COA to your vial
- Lot number on the COA equals lot number on the vial.
- Product and concentration on the COA equal the dispensed label.
- Testing date is before your dispensing date and the beyond-use date on the COA is not earlier than the one on your label.
- The laboratory named exists and does pharmaceutical testing.
If any of the four fails, you have a COA for something, but not for the medication in your hand.
What a COA cannot tell you
- Whether the drug is FDA approved. It is not; compounded drugs are not reviewed by FDA before sale, whatever the COA says.
- Whether the drug is effective or safe for you. A COA is chemistry, not a clinical trial.
- Whether the prescription behind it was lawful. See what compounders may do now.
- Whether every vial in the lot is the same as the one tested. Sampling is statistical.
- Whether a salt form was used. Some COAs state the form in the identity line; many do not. FDA has said it is not aware of a basis for compounding semaglutide sodium or acetate; ask directly. See salt forms and research use only.
What to ask for
Ask for the finished-product COA for your lot, not the API COA. If the pharmacy does not test finished lots, ask what it does instead: USP 797 requires sterility testing for certain higher-risk or longer-dated preparations, and a 503B facility operating under CGMP is expected to release-test. The vetting checklist turns these questions into a printable list, and the reviews site in this network covers how programs present COAs in their marketing.
Questions people ask
Should a 503A pharmacy be able to give me a COA?
A 503A pharmacy is not required by federal law to test every batch, and many do not for patient-specific preparations. Ask what release testing they do and who does it. A COA for the bulk active ingredient (from the API supplier) is a different document from a COA for the finished compounded product, and a pharmacy may offer the first when you asked for the second.
What does 'assay 98.5% of label claim' mean?
The measured amount of active ingredient was 98.5 percent of what the label states. The COA should print the acceptance range next to it (often 90 to 110 percent for compounded preparations). A result outside the range is a failed lot, whatever the rest of the document says.
Is a COA from the API supplier good enough?
It tells you about the powder the pharmacy started with, not the vial you inject. Sterility, endotoxin and the final concentration are properties of the finished product and can only be shown by testing the finished product.
Sources
- USP General Chapter 797, Pharmaceutical Compounding, Sterile Preparations (overview page) Accessed September 4, 2026.
- USP Compounding Standards overview (chapters 795, 797, 800 and related) Accessed September 4, 2026.
- FDA guidance: Current Good Manufacturing Practice, Guidance for Human Drug Compounding Outsourcing Facilities Under Section 503B (release testing and stability expectations) Accessed September 4, 2026.
- FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss (salt forms and dosing errors) Accessed September 4, 2026.
Canonical URL: https://formblendscompounding.com/explainers/certificate-of-analysis. Written by the FormBlends editorial team. This page is educational and is not medical advice; see the medical disclaimer.