What is the difference between HPLC and LC-MS?

HPLC separates the components of a sample and a detector, usually UV, measures how much of each there is. LC-MS adds a mass spectrometer after the separation, which measures the mass of what comes off, so it can say what the molecules are. HPLC-UV answers “how much of what was detected is the main peak”; LC-MS answers “is it the right molecule”.

Can HPLC alone confirm what a peptide is?

Not by itself. A peak at the expected retention time, compared with a reference standard, is supporting evidence, but different compounds can elute at similar times. Mass spectrometry is what shows the molecular mass.

Ultra-performance liquid chromatography is a higher-pressure form of HPLC that uses smaller particles and usually gives sharper peaks in less time. It is read in the same way as an HPLC result.

HPLC vs LC-MS: what each test tells you about a peptide

By PeptideProof · Updated 13 October 2026 · 5 min read

Peptide COAs usually name two techniques: HPLC and LC-MS. They sound alike and are often confused, but they answer different questions, and a report that has only one of them leaves a gap.

	HPLC (with UV detection)	LC-MS
Measures	How much light each separated component absorbs	The mass of each separated component
Typically used for	Purity (peak area share) and, against a standard, quantity	Identity and spotting impurities by mass
Strength	Well suited to relative amounts	Tells you what a peak actually is
Limit	A peak doesn’t prove identity; what doesn’t absorb UV isn’t seen	Not a precise measure of how much is there unless it’s calibrated for that

How they work together

In LC-MS the first half is the same kind of separation as in HPLC. The components leave the column one after another and, instead of (or as well as) being measured by UV light, they are fed into a mass spectrometer. That is why one instrument run can give both a chromatogram and a mass.

HPLC-UV gives the chromatogram, from which purity is calculated and, with a reference standard, quantity.
LC-MS assigns a mass to the main peak (identity) and can show whether a small peak is, for example, a related peptide with a slightly different mass.

Why a COA should usually show both

Purity without identity says a lot of one substance was detected but not what it is. Identity without purity says the right molecule is present but not how much else is there. Read together they are far more informative than either alone.

What to look for on a report

Both techniques named, with the UV wavelength for HPLC (often around 214–220 nm for peptides).
A measured mass or m/z value for identity, not just the word “confirmed”.
The same sample and batch for both results.

Next: reading the chromatogram and reading a mass-spec result.

Frequently asked questions

What is the difference between HPLC and LC-MS?: HPLC separates the components of a sample and a detector, usually UV, measures how much of each there is. LC-MS adds a mass spectrometer after the separation, which measures the mass of what comes off, so it can say what the molecules are. HPLC-UV answers “how much of what was detected is the main peak”; LC-MS answers “is it the right molecule”.
Can HPLC alone confirm what a peptide is?: Not by itself. A peak at the expected retention time, compared with a reference standard, is supporting evidence, but different compounds can elute at similar times. Mass spectrometry is what shows the molecular mass.
What is UPLC?: Ultra-performance liquid chromatography is a higher-pressure form of HPLC that uses smaller particles and usually gives sharper peaks in less time. It is read in the same way as an HPLC result.

See it on a real document

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