HPLC Explained for Non-Chemists
What HPLC measures, why peptide labs rely on it, and how to read a trace without a chemistry degree.
Last updated: 10 April 2026
What HPLC does
High-Performance Liquid Chromatography separates the components of a sample by how they interact with a column packed with a specific material. Different compounds elute at different times. Each compound shows up as a peak on the trace, with peak area proportional to amount.
For peptide analysis, HPLC is the workhorse purity test. A clean main peak with no significant secondary peaks indicates the sample is what it's labelled, with minimal contamination.
Reading a trace at a glance
X-axis: time. Y-axis: detector response (typically UV absorbance). The biggest peak is your main compound. Smaller peaks are impurities, degradants or related substances.
What to look for: clear axis labels, a baseline that's flat, the main peak symmetric and well-resolved, and total integration that accounts for all visible peaks. Purity is reported as the percentage of total area attributable to the main peak.
Limits of HPLC
HPLC is excellent at separating compounds by retention time but doesn't tell you the molecular identity of each peak — that's what mass spectrometry is for. A peak that looks like the right peak by retention time may not be.
This is why reputable peptide-purity testing combines HPLC (for purity) with mass spec (for identity confirmation).