Reversed-phase HPLC. The most common configuration for peptide analysis.

The output of a chromatography run: a graph of detector signal over time. Each peak is a component of the sample.

How long a component takes to travel through the chromatography column. Comparing a sample’s retention time to a reference standard is one way to check identity.

Identity confirmation by retention-time matching against a reference standard. This is the standard identity method on most accredited peptide panels. It is a consistency check rather than a definitive mass-based confirmation.

Calculating purity by measuring each peak’s area as a proportion of the total peak area. The convention for peptide purity figures.

The wavelength commonly used to detect peptides in HPLC, chosen because peptide bonds absorb strongly there.

A technique that measures the mass of molecules in a sample. Stronger evidence of identity than retention time, because it measures the molecule itself rather than its behavior on a column.

Liquid chromatography combined with mass spectrometry. Separates a sample and then measures the mass of what comes out. A stronger identity method than retention time alone, because it measures the mass of the molecule itself rather than its behavior on a column.

Limulus amebocyte lysate. The standard assay for detecting bacterial endotoxin.

The United States Pharmacopeia chapter defining sterility testing. Requires an unopened vial, which is why a full safety panel needs more product than a purity test.