Understanding Peptide Purity: Why HPLC Testing Matters
What Is HPLC?
High-Performance Liquid Chromatography (HPLC) is an analytical technique used to separate, identify, and quantify individual components within a mixture. In the context of research peptides, HPLC is the gold standard for determining purity — the percentage of the target peptide relative to all other components in a sample.
How HPLC Works
During an HPLC analysis, a dissolved peptide sample is injected into a column packed with a stationary phase (typically C18-bonded silica). A mobile phase — a mixture of water and an organic solvent like acetonitrile — is pumped through the column at high pressure. Different molecules interact with the stationary phase to varying degrees, causing them to elute (exit the column) at different times.
A UV detector at the end of the column measures absorbance at 220 nm, producing a chromatogram with peaks corresponding to each component. The area under the target peptide peak, divided by the total area of all peaks, gives the purity percentage.
Why Purity Matters for Research
Peptide purity directly impacts experimental reproducibility. Impurities — such as truncated sequences, deletion sequences, or residual protecting groups — can introduce confounding variables into assays. For most in vitro research, a purity of 95% or above is considered acceptable. For sensitive applications like receptor binding studies or cell-based assays, 98% or higher purity is recommended.
Our Commitment to Purity
At Crush Research, every batch of peptide we sell undergoes HPLC analysis by an independent third-party laboratory. We publish the full COA for each batch so you can verify purity before purchasing. We never sell peptides that test below 95% purity.