How to read a peptide certificate of analysis (COA)

Short answer: under the 2026 HHS peptide policy, the COA that matters is the one for the bulk ingredient a licensed pharmacy compounds from. It must come from an FDA-registered facility, list the original manufacturer’s address, and show results for identity, purity, potency and harmful contaminants such as endotoxins, heavy metals and microbes [1]. Appendix B of the policy lists the exact tests FDA expects [2].

Which COA counts

Most COA guides online are written for “research use only” vials. That is a different document. The HHS policy requires the pharmacy’s ingredient to come from a facility registered with FDA, with a valid COA that meets FDA’s criteria, and the original manufacturer must be FDA-registered and follow current good manufacturing practice [1]. If the ingredient comes through a repacker or reseller, that company must have checked the manufacturer and its COA [1].

You will not usually get this COA with your prescription. You can ask the pharmacy whether it has one for your batch and which company made the ingredient.

What the top of the COA must show

Appendix B lists the information a COA should carry [2]:

• the ingredient name, chemical structure, amino acid sequence, molecular formula and molecular weight;
• the manufacturer’s corporate name, address and FDA Establishment Identifier (FEI) number;
• any company that processed the ingredient, with its FEI number and address;
• any repacker, and the lab that ran the tests;
• batch number, date of synthesis, date of release, and expiration or retest date;
• grade: “Intended for human drug compounding”;
• the intended dosage form, such as injectable.

A COA without an FEI number or a manufacturer address does not meet this list.

The tests, line by line

Appendix B sets the tests below. Each COA should name the method, the limit and the result [2].

Test	What it checks	Method FDA lists
Identification / primary sequence	That the peptide is the one on the HHS list	Two or more independent methods
Assay	How much of the peptide is there, against a reference standard	HPLC (high-performance liquid chromatography)
Peptide content (net)	The share of the powder that is peptide, not water or salt	Amino acid analysis, nitrogen analysis, UV or qNMR
Peptide-related impurities	Wrong or broken peptide chains: each named impurity, any unnamed one, and the total	Two or more independent methods
Nitrosamine impurities	A class of contaminants FDA sets intake limits for	Per FDA nitrosamine guidance
Residual solvents	Solvents left over from manufacture	Gas chromatography
Elemental impurities	Heavy metals	ICP-MS
Residual TFA and fluoride	Leftovers from peptide synthesis	Ion chromatography; ion-selective electrode
Counter-ion content	The acetate salt form HHS lists	Per USP
Water content	Moisture in the powder	Karl Fischer titration
Bioburden	Microbes in the powder	Microbial count and specified organisms
Bacterial endotoxins	Toxins from bacteria	Endotoxin test (for example, LAL)

For larger peptides (8 amino acids or more), Appendix B adds higher-order structure, aggregates and biological activity [2].

How to check the manufacturer

Take the FEI number from the COA and search it in FDA’s Drug Establishments Current Registration Site (DECRS), which lists facilities currently registered to make drugs for the US market [3]. If the number is not there, ask the pharmacy why.

Red flags on a COA

• No FEI number or no manufacturer address.
• No batch number, or the same COA used for every batch.
• Purity given with no method, limit or reference standard.
• No endotoxin, microbe or heavy-metal results.
• Grade says “research use only” or “not for human use”.

What a good COA does not tell you

A complete COA shows what is in one batch of ingredient. It does not show that the compounded drug is safe or works for you. Compounded drugs are not FDA-approved, which means FDA does not review their safety, effectiveness, or quality before they are marketed [1].

Change log

• November 5, 2026: page created from HHS Appendix B.