HPLC Purity Testing: The Gold Standard for Peptide Characterization

HPLC Purity Testing: The Gold Standard for Peptide Characterization

High-Performance Liquid Chromatography (HPLC) is the most widely used analytical method for assessing peptide purity in research and manufacturing. Understanding the basics of HPLC helps researchers evaluate quality documentation and make informed purchasing decisions.

How HPLC Works

HPLC separates the components of a mixture by passing a liquid sample through a column packed with stationary phase material under high pressure. Different compounds interact with the stationary phase at different rates, causing them to elute (exit the column) at different times.

For peptide analysis, reversed-phase HPLC (RP-HPLC) is the standard method. It uses a hydrophobic stationary phase (typically C18-bonded silica) and a gradient of aqueous and organic mobile phases (usually water/acetonitrile with trifluoroacetic acid).

Reading an HPLC Chromatogram

The output is a chromatogram — a graph plotting detector response (UV absorbance, typically at 214nm or 220nm for peptides) against time. Key features:

**Main Peak** — The target peptide appears as the dominant peak. Its area relative to total peak area determines the purity percentage.

**Retention Time** — The time at which the main peak elutes. This is characteristic of the compound under specific method conditions.

**Minor Peaks** — Represent impurities — deletion sequences, truncated peptides, oxidized forms, or residual protecting groups from synthesis.

What Purity Percentages Mean

- **≥99%** — Highest research grade. Minimal impurities detected. - **≥98%** — Standard research grade. Suitable for most in-vitro applications. - **≥95%** — Acceptable for some screening applications but may contain notable impurities. - **<95%** — Generally requires further purification for sensitive research applications.

Complementary Methods

HPLC is often paired with: - **Mass Spectrometry (MS)** — Confirms molecular identity - **Amino Acid Analysis (AAA)** — Verifies sequence composition - **Endotoxin Testing (LAL)** — Detects bacterial endotoxin contamination

Pepterna's Approach

All Pepterna products undergo reversed-phase HPLC analysis with results published on the Certificate of Analysis for each batch. We use third-party laboratories for independent verification.

All products are sold for research use only. Not for use in humans or animals.