HPLC vs Mass Spectrometry for Peptide Identity
HPLC and mass spectrometry answer different questions. HPLC estimates how much of a sample is one species. Mass spectrometry tests whether that species has the expected molecular mass. A research lot should have both on the same batch record.
Research use only. This is a methods explainer for laboratory documentation, not a clinical protocol.
What HPLC reports
Reversed-phase HPLC is the workhorse purity method for synthetic peptides. The sample is separated; a detector (often UV at 214 nm) records peaks. Purity is the main-peak area percent. It does not, by itself, prove amino-acid sequence.
What mass spectrometry reports
ESI-MS or LC-MS reports m/z values. Matching the calculated monoisotopic or average mass for the sequence and counter-ion supports identity. MS can miss a co-eluting impurity that HPLC would show as a second peak, and HPLC can show a clean peak that is the wrong molecule if identity was never checked.
Why “tested” is not enough
Supplier pages often say “third-party tested” without naming the method. Independent buyer discussions consistently treat HPLC + MS as the minimum pair, and treat UV-only or MS-only as incomplete. Name the method on the product page and on the PDF.
Method · Primary question · Not sufficient alone for
HPLC-UV · Purity of the main peak · Sequence / exact identity
ESI-MS / LC-MS · Observed mass vs theory · Quantitative purity
Endotoxin (LAL) · LPS contamination · Chemical purity
What Helivex publishes
Batch files on the COA library are intended to be read as HPLC purity plus identity support. Use the checklist in how to read a COA before you accept a lot into a study.