Reading a CoA

How to read a peptide Certificate of Analysis

Q: What is the difference between HPLC purity and mass spectrometry identity confirmation?

HPLC (High-Performance Liquid Chromatography) purity is peak-area normalisation — the canonical purity metric on a CoA, reported as a percentage. Mass spectrometry confirms identity: the observed molecular mass should match the theoretical mass within about ±1 Da. Purity tells you how clean the batch is; mass spec tells you it is actually the compound claimed.

A Certificate of Analysis (CoA) is a document issued by a testing laboratory that reports the quality, purity, and identity of a specific batch of compound — the primary evidence to compare when evaluating peptide suppliers side by side.

CoA pass thresholds at a glance

HPLC purity

Pass: ≥98% (premium ≥99%) — the standard purity metric on a peptide CoA.

Mass spectrometry (identity)

Pass: observed mass = theoretical mass ±1 Da.

Endotoxin / LAL

Pass: <5 EU/mg — relevant quality control for research models.

Appearance & solubility

Should match the compound’s expected lyophilised form and solubility profile.

Independent third-party lab

Testing performed by a lab independent of the seller — New-U batches are tested by Janoshik Analytical or Freedom Diagnostics, depending on the released batch.

Using a CoA to compare suppliers

When comparing suppliers, the CoA is the one document that lets you check a claim rather than take it on trust: batch number (does it match what you are ordering), HPLC purity, mass-spectrometry identity, and the testing lab’s independence from the seller. A supplier that cannot produce a current, batch-matched CoA is not comparable on the criteria that matter.

Frequently asked questions

What is the difference between HPLC purity and mass spectrometry identity confirmation?

HPLC (High-Performance Liquid Chromatography) purity is peak-area normalisation — the canonical purity metric on a CoA, reported as a percentage. Mass spectrometry confirms identity: the observed molecular mass should match the theoretical mass within about ±1 Da. Purity tells you how clean the batch is; mass spec tells you it is actually the compound claimed.

Certificates of Analysis for released batches are published on the website. Browse the lab-verified catalogue — research use only.

Related research

Peptide supplier checklist this hub

Full "How to read a CoA" guide

New-U Certificate of Analysis gallery

Glossary: HPLC purity

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All compounds referenced are supplied for laboratory research use only and are not for human or veterinary use. Nothing on this page is medical advice.

Research use only — not for human consumption. All products are supplied strictly for laboratory research purposes.