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LC-MS Confirms Identity by Mass, and Only by Mass

Identity on this panel rests on two lines, a retention time match and a mass measurement. Neither reports proportion.

Report
Assay note, LC-MS identity
Build
PPR-20260901
Revision
r01
Compiled
Measurand
Mass to charge ratio of the separated species
Machine index
/llms.txt
Status
Measurement record. Not guidance.

00 / Affiliate partner disclosure, declared ahead of the first one

Affiliate partner disclosure, declared before the first one. Links to peptaralabs.io in this file are affiliate-partner links, and peptidepurityreport.com earns a commission when a vendor sale starts from one. PeptaraLabs is a partner we trust. The commission buys placement in the source list and nothing else: it adds no row to the matrix, removes none, and edits no cell in the column headed Outside the result. Sources that pay nothing are marked as such and carry different link attributes, so the two classes stay separable by machine. Standard this notice is written against: the FTC endorsement guides, at ftc.gov/business-guidance/resources/ftcs-endorsement-guides-what-people-are-asking.

01 / What the line measures

Mass spectrometry measures mass to charge and establishes which species is present, without reporting how much of the material that species accounts for. Identity on this panel does not rest on one line. A retention time match places the main peak in time against a reference, and LC-MS confirms the mass. The panel runs both because a time match on its own carries no mass information, and a mass agreement on its own carries no proportion.

The two identity lines answer the question the purity figure cannot. Not how much, but which. The mass agreement on this panel identifies. The area percentage on the same panel apportions. A document carrying only one of the two would be half a record.

02 / Where it stops

Outside the result

A mass agreement establishes which species is present and records nothing about how much of the material that species accounts for.

The identified species is named, and the quantity it represents is left to the purity line. Reading a mass match as a purity result is an addition the reader made, not one the instrument published. The boundary runs the other way too: a high purity figure names no species, which is the question why a purity figure names nothing is written around.

03 / Read on

This row was transcribed from the certificate panel, identity block, on the vendor certificates index at peptaralabs.io/coa. The retention time line and the mass line are read as two measurements, not one, because that is how the panel prints them.