Lab results and certificates of analysis

What a certificate of analysis is

A certificate of analysis (COA) is a test report for one batch, or lot, of a substance. FDA's Q7 guidance on making active pharmaceutical ingredients says a certificate should be issued for each batch on request, and sets out what it should carry:¹

• the name of the substance, its batch number and its date of release;
• every test performed, each with its acceptance limit and its numerical result;
• a date, and the signature of authorized staff of the quality unit; and
• the name, address and phone number of the company that originally made it.

Use those four points as a checklist for any document a seller shows you. A report with no lot number, no numbers or no date tells you little about the vial in your hands.

The tests that matter for a peptide

A useful certificate for a research peptide answers four separate questions. Each needs its own method and its own result.

An endotoxin is a toxin closely bound to the cytoplasm or cell wall of certain microorganisms and released when the cells break apart.⁷ FDA guidance notes that the USP and AAMI standards recommend testing components and finished products for pyrogens and endotoxins.⁶

A peptide medicine is held to a longer list. The European Medicines Agency's guideline on synthetic peptides, in effect from June 1, 2026, lists identification, purity (total and individual impurities), assay or content, water content, residual solvents, elemental impurities, bacterial endotoxins and microbiological purity among the tests in a peptide's specification.³ Under the European Pharmacopoeia thresholds it cites, peptide-related impurities in a medicine should be reported above 0.1%, identified above 0.5% and qualified above 1.0%.³

A certificate may also name the salt form. EMA notes that synthetic peptides usually carry acetate as the counter ion, although trifluoroacetate (TFA) or chloride are possible.³

Why lot documents matter

Laboratory testing of peptides bought online has found wide gaps between label and contents. A 2024 study test-bought semaglutide from illegal online pharmacies and analyzed the 3 vials that arrived. It found endotoxin in every vial, semaglutide content 28.56% to 38.69% above the label, and measured purity of 7.7% to 14.37% against the 99% the labels claimed.⁵

A 2018 Belgian study screened the 10 most frequently encountered falsified peptide drugs, bought from three suspected illegal internet pharmacies. It found large variation in the amount of drug per unit, purity of 5% to 75% for cysteine-containing peptides, and arsenic and lead in some samples.⁸

A certificate describes one lot, and it does not change what a product is sold for. Each of our product pages carries the label: For research use only. Not for human or veterinary use. The research peptides overview explains what these compounds are and how US rules treat them.

How to match a certificate to your vial

1. Find the lot number on the vial or its packaging, and record it with your study notes. If you cannot find one, go to step 5.
2. Look for the same product and lot number among the certificates on this page.
3. Check that the compound, the strength and the lot on the certificate match the vial exactly.
4. Read which tests were run, the method for each, the numerical results and limits, the analysis date and the name of the lab.
5. If your lot is missing, you cannot find a lot number, or any detail differs, write to support@d2cpeptides.com with the product and strength, and the lot number if you have it, before you open the vial.

How documents are listed

When certificates are published here, each is listed under its product and lot number. A certificate is added only when it can be tied to a lot we sell. Every product is in the peptide shop, and if a vial arrives with a problem, the returns page explains how to report it.