Method
Mass spectrometry: ESI-MS and LC-MS
Electrospray ionization puts a charge on the molecule so a mass analyzer can report a mass. Coupled to a liquid chromatograph, LC-MS ties that mass to a separated peak.
An identity line that says the observed mass matches the expected mass is evidence that the major measured species has the expected mass, within the tolerance the laboratory states. It is stronger than “the peak came out at the same time as the standard.” It is not, by itself, a full sequence proof. Sequence confirmation, disulfide mapping, or post-translational modification calls are additional claims. Believe them when the report says the experiment that supports them.
High-resolution instruments, including Orbitrap and QTOF systems named by some laboratories, measure mass more precisely than a low-resolution analyzer. The certificate should still say what was compared: intact mass, a fragment, or something else. A menu that says “LC-MS optional” means the base package may be retention time or a UV spectrum only. Read the package name.
Mass spectrometry does not report endotoxin, viable counts, or the milligrams in the vial unless a separate quantitative method is described. Purity still comes from the chromatographic area percent, or from whatever purity method the laboratory actually names.
If you are checking an Apollo Analytical report, use Apollo’s own Verify COA page. A verification link belongs to the laboratory that issued the report. Do not paste a different laboratory’s PDF into the wrong checker and treat a failure, or a silence, as a scientific result.