How to Read a Peptide HPLC-MS COA

What the HPLC result tells you

HPLC separates components before a detector measures their signals. An area percentage describes the assigned peak relative to the peaks included in the integration. It is not automatically a mass fraction. Wavelength, separation and integration affect what the number represents. Bachem’s analytical FAQs (opens in a new tab) explain the interpretation.

Record the detector, method and integration basis alongside the result. Avoid copying a percentage into a summary without its units and context. A chromatogram does not, by itself, answer every question about a material.

How to interpret identity evidence

Mass spectrometry measures ions by mass-to-charge ratio. Charge states and adducts can produce several signals for the same compound. Interpret the spectrum using the stated mass convention and assignments, rather than assuming every peak is a neutral molecular mass. See the Waters mass-spectrometry primer (opens in a new tab).

A mass match supports an identity assignment within the method’s limits. It is not a complete structural description or a substitute for checking the sequence and chemical modifications stated in the material record.

Purity and content are separate

Gross powder can contain water, counterions and other non-peptidic components. Net peptide content and chromatographic purity therefore answer different questions. A separately quantified target amount also needs a method, calibration basis and units. Bachem’s quality-control guide (opens in a new tab) distinguishes these measurements.

Purity

The relative composition determined by the stated analytical method.

Content

The amount or fraction measured on a defined sample basis.

Identity

Evidence supporting the proposed chemical assignment.

Match the report to its record

1. Check the exact sample name, identifier, lot and formulation.
2. Retain the laboratory, report ID, date, methods and original file.
3. Read exclusions, qualifications and missing fields before drawing conclusions.

If identifiers disagree, record the discrepancy. A test date alone does not establish an expiry date, and a historical report should not be relabeled as a current result.