---
slug: peptide-purity-coa
title: Peptide Purity, COAs, and Source Verification
canonical: https://miscsubjects.com/a/peptide-purity-coa
---

## What Is a COA
A Certificate of Analysis (COA) is a laboratory document summarizing analytical testing on a specific batch of a research compound, including compound name, batch/lot number, analytical methods, purity results, testing date, and laboratory identification. [c1]

## Typical COA Contents for Peptides
Non-GMP COAs commonly list amino acid sequence, modifications, purity (often by RP-HPLC), mass spectral data (MS), and appearance. GMP COAs are more comprehensive, including additional specifications. [c2]

## Third-Party Testing and Verification Methods
Independent labs use HPLC for purity and Mass Spectrometry (MS) for identity confirmation. Accredited labs (e.g., ISO/IEC 17025) provide validated testing for research peptides. [c3][c4]

## American-Made and Manufacturing Standards
Vendors may claim U.S. sourcing or third-party testing, but buyers should verify lot-specific COAs match the product and check for endotoxin or sterility data beyond basic purity. [c5]

## Differentiating Sources and Grey Market Risks
Purity percentages (e.g., ≥99%) confirm identity but do not guarantee sterility or absence of endotoxins; grey-market products labeled Research Use Only may lack these controls. Independent testing platforms report on vendor consistency across batches. [c6]

## How Buyers Can Verify
Cross-check lot numbers on COA against vial; confirm testing lab independence; request additional assays like endotoxin if relevant for research. No human clinical data supports general claims on peptide sourcing outcomes.
