Every batch of research peptide produced under proper quality control comes with a Certificate of Analysis (CoA). The CoA is the document that links a specific batch to specific analytical data — HPLC purity, mass spectrometry identification, moisture content, and physical characterisation. Without a CoA, you have no documentation that the compound in the vial matches the compound on the label. With a CoA from a poorly-equipped supplier, you have documentation that may not be reliable. This article explains what a proper research peptide CoA should contain and what to verify before that material enters your laboratory inventory.

What a Proper CoA Contains

A research-grade CoA for a peptide compound should include, at minimum:

• Product identification — compound name, sequence (where applicable), CAS number, molecular formula, and molecular weight.
• Batch number — a unique identifier traceable to the synthesis run and QC analysis cycle.
• Manufacturing date and analysis date — both should be recent, with analysis date typically within weeks of shipment.
• HPLC purity result — typically ≥99% for research-grade material, with the chromatogram or peak integration table.
• Mass spectrometry result — observed monoisotopic mass compared against theoretical mass for the target sequence, confirming compound identity.
• Karl Fischer titration — moisture content, typically reported as a percentage, important for lyophilised material stability.
• Appearance — physical description of the lyophilised material (white amorphous solid, off-white powder, etc.).
• Storage recommendations — temperature range, light exposure guidance, reconstitution notes.
• Signature and laboratory identification — analyst name, QC manager signature, laboratory address.

Reading the HPLC Section

The HPLC purity result is the most important single number on the CoA. A proper presentation includes:

• The integrated chromatogram showing all detected peaks
• Retention time of the target peak
• Peak area as a percentage of total integrated area
• The HPLC method conditions (column, mobile phase composition, flow rate, detection wavelength)

Red flags in the HPLC section: a single number (“≥99%”) with no chromatogram, missing method conditions, a chromatogram that shows multiple unidentified peaks comparable in area to the target peak, or method conditions that are clearly unsuitable for the compound class (e.g. a non-reversed-phase method for a typical research peptide).

Reading the Mass Spectrometry Section

Mass spectrometry confirms compound identity. For a peptide, the CoA should report:

• Theoretical monoisotopic mass for the target sequence
• Observed mass (typically electrospray ionisation, ESI-MS)
• Mass accuracy or error (in ppm or Da)

For a correctly-identified compound, the observed mass should match the theoretical mass within typical mass spectrometer accuracy (under 5 ppm for high-resolution instruments, under 0.5 Da for unit-resolution instruments). A mismatch indicates the compound is not what the label says it is — either a synthesis error, a labelling error, or a deliberately substituted compound.

Reading the Karl Fischer Titration

Karl Fischer titration measures water content in the lyophilised material. Excess water accelerates hydrolytic degradation and indicates incomplete freeze-drying or improper packaging. Typical research-grade lyophilised peptides report moisture content under 5%, often under 2%. Values above 10% suggest material that will not maintain stated shelf-life and should be questioned.

Common CoA Failures and Red Flags

When evaluating a supplier or batch, watch for these issues:

• No CoA at all. Material shipped without documentation has no analytical traceability. Walk away.
• Generic CoA, no batch number. A boilerplate document that lists the compound but not the specific batch you received is not a real CoA — it is marketing material.
• CoA dates that do not match. Analysis date significantly older than ship date suggests stored inventory of indeterminate age.
• Missing chromatogram. A number without the supporting data cannot be verified.
• Mass spec missing or vague. “Confirmed by MS” with no actual data is not verification.
• Suspicious purity claims. 99.9% or “100% pure” claims should be viewed with scepticism — modern HPLC reports purity to two significant figures, and ≥99% is the practical limit of meaningful claim.
• No analyst signature or laboratory identification. Anonymous CoAs cannot be followed up if questions arise.

What to Do With a CoA Once You Receive It

Standard laboratory protocol for incoming research peptide material:

1. Match the batch number on the CoA against the batch number on the vial label.
2. Confirm compound name, sequence, and molecular weight match between CoA, vial, and order documentation.
3. Verify HPLC purity is at or above the threshold required by your protocol (typically ≥98% for most research applications, ≥99% for publication-grade work).
4. Confirm mass spectrometry data matches expected compound identity.
5. File the CoA in your laboratory document management system with date of receipt and storage location.
6. For batch-sensitive work, retain the CoA for the full retention period required by your institutional protocols (typically 5-10 years for regulated research environments).

What Chempeptides Provides

Every batch of research peptide sold by Chempeptides has an associated CoA documenting HPLC purity (≥99%), mass spectrometry identification, Karl Fischer moisture content, and physical characterisation. CoAs are available on request via the contact form after order placement, referenced by batch number.

For institutional procurement that requires CoA delivery as part of the order process (e.g. academic accounts, CRO supply contracts), we can arrange for CoA to ship with the physical product. Reach out to discuss procurement workflow requirements.

For qualified researchers ready to procure verified research peptides: browse the catalogue. Research-use only.