Purity, identity and peptide content answer different questions.

Start with the question, then read the result.

A percentage on a product page is not a complete description of a research sample. Identity, chromatographic purity and peptide content describe different aspects of the material. Reading them separately makes the supporting evidence easier to evaluate. This guide explains those distinctions; it does not certify a Lotreva product.

Sources: GenScript: peptide synthesis and net peptide content

Identity: what is the material?

Identity testing examines whether the material is consistent with the intended compound. The reported analytical method matters: a result should be read alongside the method, sample identifier and the laboratory's interpretation. GenScript lists mass-spectrometric and other analytical services in its quality-control information. A buyer should request the relevant record rather than infer identity from a label alone.

Sources: GenScript: AccuPep quality-control methods

Purity: what did the method detect?

Bachem describes peptide purity as commonly determined by reversed-phase HPLC, relative to detected impurities under the stated analytical conditions. The result is method-specific. It is not a universal statement that every possible contaminant has been assessed.

When reviewing a purity value, keep the chromatogram, method information and lot identifier together. Do not convert a broad claim such as “high purity” into an unreported numerical result.

Sources: Bachem: peptide content and concentration

Content: how much peptide is represented?

The gross mass of a dried preparation can include water, solvents, counterions and salts in addition to peptide material. GenScript distinguishes net peptide content from the purity of the target sequence within the peptide portion. A gross vial weight, a purity percentage and a net-content result therefore should not be substituted for one another.

Use the definitions and analytical data supplied for the specific lot. If the basis of a quantity claim is unclear, ask the supplier or testing laboratory to clarify it before using that number in research documentation.