How to Read a Peptide COA

A Certificate of Analysis (COA) is the single most important document when sourcing research peptides. It provides analytical proof that the compound is what it claims to be, at the stated purity. Here's how to read one and verify it independently.

What a COA Should Include

• Compound name and batch/lot number — identifies the specific product and production batch
• HPLC purity result — the percentage purity by peak area (should be ≥98%, ideally ≥99%)
• HPLC chromatogram — the actual chart showing the purity peak and any impurity peaks
• Mass spectrometry (MS) result — confirms molecular identity by matching observed mass to expected molecular weight
• Water content (Karl Fischer or similar) — important for peptides since excess moisture indicates degradation risk
• Appearance description — should match what you receive (e.g., "white lyophilized powder")
• Third-party verification reference — e.g., Janoshik batch number for independent confirmation

Understanding HPLC Purity

HPLC (High-Performance Liquid Chromatography) separates the compounds in a sample and quantifies them by peak area. The purity percentage represents the main peptide peak as a proportion of total peak area. A result of "≥99.2%" means the target peptide comprises 99.2% of the sample, with ≤0.8% being impurities (deletion sequences, oxidation products, or other synthesis byproducts).

What to look for: A single dominant peak (the target peptide) with minimal secondary peaks. Multiple large secondary peaks suggest poor synthesis or purification.

Understanding Mass Spectrometry

Mass spec confirms identity — it measures the molecular weight of the compound and compares it to the known molecular weight. If the MS result matches the expected molecular weight within standard tolerance (typically ±0.1%), the compound is confirmed as the stated peptide. This prevents substitution fraud (selling a cheap peptide labeled as an expensive one).

Janoshik Verification

Janoshik is an independent analytical testing laboratory that researchers use to verify COA claims. When a vendor provides a Janoshik-verified COA, it means the testing was conducted independently — not self-reported by the vendor. You can verify any Janoshik result at verify.janoshik.com using the batch reference number.

QSC Peptides publishes Janoshik-verified COAs on every product page. This is one of the key reasons the Clavicular Ascension Stack is sourced from QSC — every batch is independently verified before distribution.

Red Flags in a COA

• No chromatogram — just a purity number without the chart is easy to fabricate
• No mass spec — purity without identity confirmation means you don't know what compound is pure
• No batch number — can't be independently verified
• "In-house testing only" — no third-party verification means self-reported results
• Suspiciously round numbers — real HPLC results have decimal precision (e.g., 99.23%, not "99%")