When you see a research peptide advertised at "99% purity," what does that number actually mean — and why does it matter? This guide explains it in plain terms.
What purity measures
Purity is the percentage of material in a vial that is the intended peptide, as opposed to impurities such as truncated or deletion sequences and residual synthesis reagents. 99% purity means 99% of the peptide content is the target compound.
How purity is measured
The standard method is High-Performance Liquid Chromatography (HPLC), which separates a sample's components and quantifies each as a percentage. The main peak is the target peptide; smaller peaks are impurities.
Why it matters for research
In laboratory research, impurities can confound results. Higher purity means more reproducible, reliable data — which is why research-grade peptides are typically specified at 98–99%+.
Purity vs identity
Purity (how much is the target) differs from identity (whether it is the correct compound). Identity is confirmed separately by mass spectrometry. A complete Certificate of Analysis reports both.
At Peptide Pal
Every batch is verified to 99%+ purity by third-party HPLC. Browse our research peptides.
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