Certificate of Analysis methodology

Every BluGen lot ships with a Certificate of Analysis (CoA) that reports five things: identity, HPLC purity, net peptide content, water content, and residual solvents. This page documents the analytical methods used to produce each value, the acceptance criteria we hold lots to before release, and the format in which we publish the results.

1. Identity confirmation — Mass spectrometry

Peptide identity is confirmed by electrospray-ionization mass spectrometry (ESI-MS) against the calculated monoisotopic mass for the published sequence. Lots release only when the observed mass aligns with the calculated mass within the method tolerance and the charge-state envelope is consistent with a single peptide species.

For modified peptides (acetate counterion, palmitic acid conjugation, C-terminal amidation, etc.), the modification is verified by mass shift relative to the unmodified parent sequence.

2. Purity — Reverse-phase HPLC

Reverse-phase high-performance liquid chromatography (RP-HPLC) at 214 nm UV detection (peptide-bond absorbance) is the standard purity method. Acceptance criterion for the standard research-grade catalog is ≥98% area purity. Chromatograms are retained per lot and available to qualified institutional buyers on request.

3. Net peptide content

HPLC area purity does not equal mass-on-vial. Lyophilized peptides ship with water, counterion, and trace solvent contributions to gross mass. Net peptide content is calculated and reported on the CoA so research molarity calculations use the correct active mass.

4. Water content — Karl Fischer titration

Karl Fischer coulometric titration measures the residual water in the lyophilized cake. Water content affects both stability and net peptide content calculations, and is reported on every CoA.

5. Residual solvents — Gas chromatography

Residual solvents from synthesis (acetonitrile, TFA, DMF, methanol) are quantified by gas chromatography against ICH Q3C class-3 limits. Lots exceeding the limit are not released.

What the CoA looks like

Every CoA carries: lot number, manufacture date, ship date, expiration, sequence (and any modification), molecular formula, monoisotopic mass, calculated mass, observed mass, HPLC purity (%), net peptide content (%), water content (%), residual solvent panel, storage instruction, and the signature of the releasing analyst.

Lot retention and re-testing

Retention samples are held for the full advertised stability window. Lots can be re-tested on request — typical re-test triggers include extended storage past the expiration window, customer-reported identity discrepancies, or scheduled stability checkpoints.

Methodology updates

This page is reviewed quarterly. Material changes to acceptance criteria, instrument platforms, or panel composition are dated below.

Last updated: 2026.