Purity
The relative result reported for detected components under the stated purity analysis.
Laboratory analysis guide
HPLC Purity vs Compound Identity
Reported HPLC purity and compound identity describe different analytical questions. This guide explains how to distinguish them and how to read each result within the limits of a peptide laboratory report.
What HPLC purity measures
High-performance liquid chromatography separates detected components under the conditions described by the laboratory. A reported HPLC purity percentage generally describes the relative chromatographic response assigned to the reported component within that analysis.
The value is tied to the stated sample, method and detection conditions. It should be read from the original report together with any chromatogram, qualifiers or limitations the laboratory provides.
What the percentage does not establish
A purity percentage does not by itself establish that the detected component is the compound named on the label. It also does not independently report the sample’s net content, endotoxin result or sterility result.
Those are separate analytical questions. No conclusion about them should be inferred from an HPLC purity figure alone.
Identity requires its own evidence
Identity testing is intended to assess whether an observed property or set of properties is consistent with the named compound. A laboratory may use a separate analytical method because identity and chromatographic purity answer different questions. Read only the methods and conclusions actually recorded in the report.
Keep each test category separate
Identity
Whether the measured characteristics are consistent with the compound named in the report.
Net content
The reported quantity of material in the tested sample.
Endotoxin
A separate test category that should be treated as present only when explicitly reported.
Sterility
A separate test category that should not be inferred from purity or identity data.
Reading HPLC information with PEPY batch documentation
First match the compound, strength and batch number shown in the report to the batch documentation being reviewed. Then identify which test categories are explicitly listed and read each result within the scope stated by the laboratory.
A blank or absent category is not a reported result. The document for one identified batch should not be used to draw conclusions about another batch or future material.
Educational laboratory reference only. Conclusions should be limited to the tests, sample and batch information explicitly reported in the original laboratory document.