# HPLC vs Mass Spec: What Each Peptide Test Actually Tells You

_Mass spectrometry confirms identity; HPLC measures purity. What each peptide test proves, and why one without the other is incomplete. Educational only._

Source: https://growthguyscanada.coupons/articles/hplc-vs-mass-spec-peptide-testing.html · Updated: June 17, 2026 · TorontoHealth — educational only, not medical advice.


> **The core idea:** HPLC and mass spectrometry answer different questions. Mass spec confirms *identity* — is this the molecule it claims to be? HPLC measures *purity* — how much of the sample is that molecule versus everything else? A complete COA needs both.

## What mass spec proves

Mass spectrometry weighs the molecule and matches it to the expected mass. It answers "is this the right compound?" — but on its own it says little about how much filler or by-product rides along.

## What HPLC proves

HPLC separates a sample into its components and reports the percentage that is the target compound. It answers "how clean is it?" — but on its own it doesn't confirm the main peak is the right molecule.

## Why one alone isn't enough

A high HPLC purity number on the wrong molecule is meaningless, and a confirmed identity with unknown purity is half a picture. Read both, together.

Related: [purity vs identity on a COA](/articles/coa-purity-vs-identity.html) · [how to read a COA](/articles/how-to-read-a-peptide-coa.html).

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_General educational information, not claims about any specific company. For research and educational purposes only. Not medical advice. Posts may contain affiliate links._