How to Read a Peptide COA — Field-by-Field Guide | Regena Peptides

A COA is an analytical report produced by a testing laboratory for a specific batch of a specific compound. It records what the laboratory measured — purity, identity, related impurities, water content — and gives the receiving researcher the evidence needed to decide whether the batch meets the project specification.

A credible COA is produced by an independent third-party laboratory (Janoshik Analytical is the industry-standard verifier in Europe), references a specific batch number that matches the vial cap, is dated within the shelf-life window for the compound, and uses analytical methods appropriate to the chemistry of the molecule.

The batch number is the first thing to check: it must match the batch number printed on the vial cap exactly. A COA that references a different batch is not valid for the vial in front of you, even if the compound name matches. The report date matters because most lyophilised peptides have a shelf-life window measured in months from the date of manufacture or release; a COA dated outside that window is a stability flag, not a release certificate.

Regena prints the batch number on the vial cap and on the outer packaging, and publishes the matching COA on the /coa lab reports page within 24 hours of independent release.

The COA must name the compound exactly and state both the theoretical molecular weight (calculated from the sequence) and the measured molecular weight from the mass-spectrometry panel. The two numbers should match within instrument tolerance — typically a fraction of one Dalton for a peptide in the 1–5 kDa range.

If the measured molecular weight does not match the theoretical molecular weight, the batch is not what the label says it is — that is the single most serious COA flag and should always be referred back to the supplier before any reconstitution.

The HPLC chromatogram shows the main peak (the target peptide) and any secondary peaks (related impurities). The main-peak purity is reported as a percentage of total integrated peak area. For research-grade peptides the credible release threshold is ≥98.0%, and Regena's internal minimum specification is ≥99.0%.

A main-peak purity below the specification does not automatically mean the batch is unsafe to use for an in-vitro protocol, but it does mean the secondary peaks should be characterised before the batch is committed to a stability or comparator study — otherwise project conclusions can be contaminated by an unknown impurity contribution.

Related impurities are the secondary peaks on the HPLC chromatogram. For peptide chemistry the common sources are des-amino byproducts (a residue dropped during synthesis), oxidation products (typically methionine or tryptophan oxidation), deamidation products (asparagine or glutamine converted) and incomplete coupling products. A well-characterised batch will identify the major related impurities and report each as a percentage of total peak area.

A clean batch shows a single dominant peak with related impurities in the low-single-digit total. A messier batch shows multiple secondary peaks; that is not always disqualifying, but it changes the experimental risk profile and should be cross-referenced against the project specification.

Lyophilised peptides contain residual water from the freeze-drying process. The water content is measured by Karl Fischer titration or thermogravimetric analysis and reported as a percentage. Most credible lyophilised peptide batches sit between 2% and 8% water content; anything above the published specification is a stability flag because residual water accelerates degradation in the lyophilised state.

A high water-content batch is not automatically unsafe — it just has a shorter realistic stability window and should be reconstituted sooner rather than stored.

The mass-spectrometry panel confirms that the main HPLC peak is in fact the compound named on the label. It does this by measuring the molecular weight of the peak and comparing it to the theoretical molecular weight calculated from the sequence. The two should match within instrument tolerance.

For peptides with modifications (e.g. tesamorelin's trans-3-hexenoyl group, or analogues with fatty-acid side-chains), the mass-spectrometry report should explicitly confirm the modification — not just the base sequence — or the identity confirmation is incomplete.

A credible COA is signed by an identified analyst from an identified laboratory. A COA from an anonymous internal laboratory is not third-party verification; a COA from a named external laboratory with a known address and published methods is. For Regena batches that signature is from Janoshik Analytical or an orthogonal independent laboratory of equivalent standing.

If the COA does not name the laboratory or the analyst, treat the document as a supplier-internal report and ask for an independent third-party COA before committing the batch to a protocol.

Run this checklist on every batch before reconstitution: (1) batch number on vial = batch number on COA; (2) report dated within the shelf-life window; (3) compound name matches the label; (4) measured molecular weight matches theoretical within tolerance; (5) HPLC main-peak purity meets the project specification; (6) related impurities total within the project tolerance; (7) water content within published specification; (8) COA signed by a named analyst from an identified independent laboratory.

Any single failure is a flag, not a fatal — but all eight passing is the baseline for a confident reconstitution. The Regena consultations team will walk a new laboratory through the checklist once and the workflow becomes second nature.