Purity is the single most important quality signal for a research peptide. Here's how it's measured, and why a Certificate of Analysis is worth asking for.
Research is only as reliable as the material behind it. Two vials labelled the same can behave very differently if one is 99% pure and the other is full of impurities. That's why purity — and the paperwork that proves it — sits at the centre of peptide quality.
How purity is measured
The two workhorse techniques are HPLC (high-performance liquid chromatography), which separates a sample into its components so the target peptide can be quantified, and mass spectrometry, which confirms the compound's identity by its molecular mass. Together they answer the two questions that matter most: is this the right peptide, and how much of the vial is actually it?
What “≥99% purity” means
A purity figure of ≥99% means that, by HPLC, at least 99% of the peptide content is the target compound. Every Negra Peptides batch is tested to that threshold before it's released — higher purity means fewer unknown variables in your results.
The Certificate of Analysis
A Certificate of Analysis (CoA) is the third-party lab's report for a specific batch: the identity confirmation, the purity result, and the batch reference. Asking for a CoA is one of the simplest ways to check a supplier is serious. We hold one on file for every batch and provide it on request.
If a supplier can't produce a batch-specific CoA, that's a signal worth paying attention to.
This article is for general educational purposes only and relates to laboratory research use. It is not medical, veterinary or professional advice. All Negra Peptides products are supplied strictly for in-vitro research — For Research Use Only, Not for Human Consumption.