Analytical methods

What we test, and why

A purity claim only means something if you know what was measured and how. Every lot released under the 321 Peptides label is evaluated against the same panel: identity, purity, net content, appearance, and residual moisture. Results are consolidated into one batch-specific Certificate of Analysis rather than split across separate reports.

Purity is assessed by an independent third-party laboratory. We do not release a lot on in-house purity data alone.

Identity — mass spectrometry (LC-MS)

Liquid chromatography coupled to mass spectrometry confirms that the molecule in the vial is the molecule on the label. The measured mass is compared against the theoretical monoisotopic or average mass calculated from the declared sequence.

For blends, each component is confirmed separately. Co-formulation does not create a new molecule, and the certificate reports each compound on its own line.

A lot is rejected if the observed mass does not fall within the expected tolerance of the theoretical value.

Purity — HPLC-UV

Reversed-phase high-performance liquid chromatography separates the target compound from process-related impurities. Detection is by UV absorbance, and purity is reported as the area percentage of the main peak relative to total integrated peak area.

The release target is ≥99% for peptide products. The figure printed on each certificate is the value measured for that specific batch, which is why numbers differ slightly between lots — a supplier reporting an identical figure on every batch is reporting a specification, not a measurement.

• Column: C18 reversed phase
• Detection: UV, photodiode array
• Reporting: area percent of the principal peak
• Release criterion: ≥99.0% for peptide products

Net content

Vials are checked to confirm that the quantity of material present meets or exceeds the nominal fill stated on the label. The measured value is printed on the certificate, and it is normal for it to sit marginally above the nominal figure.

Residual moisture and appearance

Lyophilized material is checked for residual water content, since moisture affects stability during storage. Appearance is recorded as observed — typically a white lyophilized powder, or a clear colorless solution for aqueous products.

Products that are not peptides

Not every item in the catalog is a peptide, and applying peptide test language to them would be misleading. NAD+ is a dinucleotide coenzyme and is evaluated on the basis appropriate to that molecule. Bacteriostatic water is a preserved aqueous solution and is assessed against composition and quality specifications, not peptide HPLC purity.

Reading a certificate

Every certificate is tied to a lot code, and that code is printed on the vial. Match the two before you rely on the document.

• Lot — the batch identifier printed on the vial
• Reported — the date the analytical results were issued
• Identity (LC-MS) — confirmed or rejected
• Purity (HPLC-UV) — area percent for that batch
• Net content — measured quantity in the vial
• Appearance and water content — as observed at release

Certificates for every released lot are held in the COA library and remain available after the batch sells out, so records stay verifiable long after the vial is gone.