Testing
HPLC vs. Mass Spectrometry: What Each Test Actually Proves
ALTR Research Team · August 5, 2026 · 5 min read
It's common to see 'HPLC tested' used as shorthand for 'verified,' but HPLC and mass spectrometry answer genuinely different questions, and a rigorous verification process needs both.
What HPLC measures
High-performance liquid chromatography separates the components of a sample as they pass through a column, then measures the relative size of each resulting peak. The peak attributed to the target compound, expressed as a percentage of total peak area, becomes the reported purity. HPLC is excellent at quantifying how much of something is present relative to everything else in the vial — but on its own, it assumes you already know what that 'something' is.
What mass spec measures
Mass spectrometry ionizes a sample and measures the mass-to-charge ratio of the resulting fragments, producing a molecular fingerprint that can be compared against the expected structure of the target compound. This is an identity test, not a quantity test — it answers whether the molecule is actually what it's labeled as, independent of how much of it there is.
Why you need both
A sample can return a high HPLC purity reading for the wrong compound entirely, if that compound happens to elute at a similar point and no identity confirmation is run. Conversely, a correctly identified compound could still be present at a purity too low to be a meaningful research reagent. Pairing HPLC with LC-MS closes both gaps: one confirms quantity, the other confirms identity.
Every batch we release is run through both. It's slower and more expensive than a single-method process, and it's also the only version of 'tested' that we think is worth putting our name on.
Every batch we sell ships with independent, lot-specific testing.
Browse the current catalogue or look up a batch's Certificate of Analysis on the Lab Results page.
