Educational Resource
Testing & COAs
Understanding analytical documentation is the foundation of evaluating research compounds. This hub covers the methods, documents, and terminology researchers need to assess quality claims.
Articles & Guides
How to Read a Certificate of Analysis
A COA is the primary document researchers use to evaluate a research compound. This guide explains every field — what it means, what to look for, and what should raise questions.
HPLC Explained
High-performance liquid chromatography is the most common method for measuring peptide purity. Here is how it works, what it measures, and what it does not.
LC-MS Explained
Liquid chromatography–mass spectrometry combines separation with molecular identification. It answers a different question than HPLC — and both matter.
Purity vs. Identity: Why Both Matter
A compound can be 99% pure and still be the wrong compound. Understanding the difference between purity testing and identity testing is fundamental to evaluating research materials.
Net Peptide Content
A headline purity percentage does not tell you how much active peptide is in the vial. Net peptide content — accounting for water, TFA, and counterions — is the number that matters.
Third-Party Testing: What It Means and What It Doesn't
The phrase "third-party tested" appears on almost every RUO supplier's website. What does it actually mean — and how do you verify it?
Batch Testing and Lot Numbers
Lot-specific documentation is the difference between a COA that applies to your compound and one that applies to a different production run. Here is why it matters.
Quick Reference
HPLC
High-performance liquid chromatography. Measures compound purity by separating components in a solution.
LC-MS
Liquid chromatography–mass spectrometry. Identifies a compound by its molecular mass. Confirms identity, not just purity.
COA
Certificate of Analysis. The document that records the results of testing for a specific batch of a compound.
Lot Number
A unique identifier for a specific production batch. Allows a COA to be matched to the exact material tested.
Net Peptide Content
The percentage of a sample that is active peptide, after accounting for water, TFA, and other counterions.
Endotoxin
Bacterial cell-wall components that can cause inflammatory responses. Endotoxin testing is relevant for research-grade materials.
Sterility
Confirmation that a compound is free from viable microorganisms. Relevant for certain research applications.
TFA
Trifluoroacetic acid. A common counterion in peptide synthesis that affects net peptide content calculations.
See how companies score on testing and COAs.
The RUO Company Directory compares every reviewed company across six criteria.