How to read a peptide Certificate of Analysis (COA)

What a COA is

A Certificate of Analysis (COA) is a lab-issued document attesting that a specific batch of a peptide has been tested and met defined specifications for identity, purity, and (in higher-quality regimes) sterility, endotoxin load, and heavy-metal content. A COA is a vendor accountability mechanism: it lets a buyer verify that the substance in the vial matches the label without having to commission their own assay.

For research-peptide buyers, the COA is the single most useful artifact a vendor can publish. Pepticker’s 7-category testing rubric is anchored to the data a competent COA contains, and our Vendor Trust Score uses COA discipline as one of five components.

The Pepticker 7-category COA rubric

Every vendor we grade is scored on whether the published COA covers the seven categories below. Each line is a binary 0/1 (or 0.5 partial), summed to produce the visible testing score.

Acronyms decoded

• HPLC (High-Performance Liquid Chromatography) — the workhorse purity assay. The peptide is forced through a column under high pressure, and a detector counts the peaks. The target peptide should be one tall, narrow peak; impurities show up as smaller peaks. Purity is reported as a percentage of total peak area.
• LC-MS (Liquid Chromatography – Mass Spectrometry) — same column separation, plus a mass-spec detector that measures the molecular weight of each peak. This is how a lab confirms which peptide is in the vial, not just that something is in the vial. The reported observed mass should match the theoretical mass of the labeled peptide within ~1 Da.
• GC-MS (Gas Chromatography – Mass Spectrometry) — used for residual-solvent screens (acetonitrile, TFA, DMF). Less common on a routine peptide COA, but appears on pharmaceutical-grade documents.
• ICP-MS (Inductively Coupled Plasma Mass Spectrometry) — the standard heavy-metals screen. Reports lead / cadmium / mercury / arsenic in parts-per-million or parts-per-billion against ICH Q3D limits.
• LAL endotoxin — Limulus Amebocyte Lysate assay, derived from horseshoe-crab blood. Detects bacterial endotoxin (lipopolysaccharide) at picogram-per-mL sensitivity. Pharmaceutical-grade peptides typically specify <0.25 EU/mg.
• USP <71> sterility — the U.S. Pharmacopeia chapter governing sterility testing. The product is incubated for 14 days in two growth media; no observable bacterial or fungal growth is the pass criterion. This is a much stronger claim than a single-timepoint plate count.
• MALDI-TOF — Matrix-Assisted Laser Desorption/Ionization, Time-of-Flight. An alternative mass-spec method common in academic peptide labs. On a vendor COA it serves the same purpose as LC-MS.

What a credible COA looks like

A useful COA is batch-specific and unambiguous. It pins each test result to a specific lot of product so the buyer can match the document to the vial in hand. The minimum fields a credible COA carries:

• Product name and CAS number (or other unique identifier) printed on the document.
• Batch / lot number that matches the label on the vial.
• Test date and analyst signature (or lab director sign-off).
• Named laboratory issuing the document — not the vendor itself testing in-house unless they hold a third-party accreditation.
• Specification limits (e.g., “purity ≥ 97.0%”) alongside the measured result, so a reader can see whether the measurement passed.
• A purity chromatogram or a mass-spec spectrum image — not just a number in a table.
• A copy of the vendor’s scope of testing (which categories the lab was contracted to assess).

Tells of a low-quality COA

• No batch number. A COA without a lot identifier cannot be matched to the specific vial shipped. It is, in practice, a marketing brochure.
• No signing analyst or lab director. Anonymous COAs cannot be verified or contested; reputable labs identify the responsible scientist.
• Generic product name. “BPC-157 (5 mg/vial)” with no CAS, no sequence, and no manufacturer code is unspecific to the actual product on the COA.
• Vague purity claims. “Purity: high” or “Purity: >95%” (without the actual measured value or chromatogram) is unverifiable.
• Missing chromatogram image. A purity number with no visual peak trace is easy to fabricate; a published chromatogram is much harder to forge convincingly.
• Stale dates. A COA dated more than three months before the shipment date may not reflect the current batch. Pepticker disqualifies COAs older than three months from rubric scoring.
• In-house testing without accreditation. Some vendors run their own HPLC. That is fine as a screen, but the COA loses independent-lab credibility unless the vendor publishes ISO 17025 accreditation or equivalent.

Three COA disclosure regimes

Vendor COA practices fall into roughly three tiers — in ascending order of buyer trust:

• No COA disclosed. The vendor does not publish a Certificate of Analysis at all. This is the lowest-trust regime and usually correlates with low Pepticker testing scores.
• “COA available on request.” The COA is sent by email after purchase or after a support ticket. Better than nothing, but the buyer can’t verify the document before committing dollars, and the per-batch cadence is opaque.
• QR-coded batch-specific COA on the vial or product page. Each vial carries (or is linked to) the lot-matched COA, accessible without an account. This is the strongest regime for a research-channel vendor and is what tier-1 Pepticker entries typically deliver.

The independent-lab shortlist

For research-peptide COAs, a small number of contract labs do most of the work. Vendor COAs from these labs are easier to cross-check because the labs themselves publish methods, scope of accreditation, and (in some cases) analyst rosters:

• Janoshik Analytical — Czech Republic; the de-facto default for the research-peptide channel. Publishes HPLC and LC-MS results.
• Kovera — multi-analyte testing, including endotoxin and sterility regimes.
• Finnrick Analytical — boutique HPLC + MS provider.
• MZ Biolabs — U.S.-based; broader pharma-style testing menu.
• ILS Labs (Industrial Laboratories Services) — GMP-capable for higher-tier vendors.

Pepticker only credits COAs from named third-party labs in the rubric. Vendor self-reports do not count toward the testing score.

Where to look next

Frequently asked questions

Is a COA the same as third-party testing?

Not necessarily. A COA is a document; third-party testing is the regime under which that document was generated. A COA from an in-house vendor lab is still a COA but does not carry the same credibility as one issued by an independent contract laboratory. Look for the issuing lab’s name, accreditation status, and whether the lab is structurally separate from the vendor.

What purity threshold should I look for?

Pepticker’s rubric credits net purity at 97% or higher (HPLC, area-percent at 220 nm). The research-peptide channel commonly publishes 98–99%; pharmaceutical-grade specifications are typically ≥ 99% with tighter specifications on individual related impurities.

Why does the rubric require batch-matched COAs?

Peptide synthesis runs vary batch-to-batch. A COA generated for a batch shipped six months ago tells you very little about the vial in your hand today. Batch-matched documents are the only way to make the certificate falsifiable against the actual product.

What does “endotoxin within limits” mean numerically?

FDA pyrogen guidance and USP <85> derive limits from a per-kg threshold (typically 5 EU/kg for parenteral non-intrathecal products). Pharmaceutical-grade peptides typically specify < 0.25 EU/mg as a practical cap. Research-channel COAs often report a measured value rather than a fixed cap; either is informative if the measurement is shown.

How often should COAs be regenerated?

Per batch. Some labs also re-test stability at fixed intervals (e.g., 6 / 12 / 24 months). Pepticker disqualifies COAs older than three months from current rubric scoring.

Is HPLC enough on its own?

HPLC alone establishes purity but not identity — a peak at the right retention time could be the target peptide or a related impurity with similar chromatographic behavior. Identity confirmation requires a mass-spec method (LC-MS, MALDI-TOF). A complete COA pairs HPLC purity with mass-spec identity, plus endotoxin / sterility / heavy-metals where the vendor claims pharmaceutical-style discipline.