How to read a Certificate of Analysis
What each section of a COA actually proves, which fields suppliers commonly omit, and the eight checks that separate a real COA from a marketing document.
Resources
Reference material, not marketing.
Most suppliers publish a purity number and stop. These are the documents we wish every supplier published — written for people who actually have to evaluate a lot.
Storage, stability & handling
Lyophilized versus reconstituted stability, freeze-thaw effects, light and moisture sensitivity, and how to store each compound class in your own facility.
The five-point release panel
HPLC, mass spec, LAL endotoxin, USP <71> sterility and fill-weight verification — what each one answers and why a purity figure alone is not enough.
How research peptides are made
Solid-phase peptide synthesis, cleavage and deprotection, preparative HPLC purification, lyophilization and controlled fill — the twelve documented steps.
Frequently asked questions
Purity specifications, testing, international shipping, wholesale minimums and the research-use-only framework we operate under.
Partner program
Commission tiers, cookie window, payout schedule, and the content rules every partner agrees to when promoting research-use-only materials.
Specification glossary
The terms on a COA, in plain language.
| Term | What it means | Why it matters |
|---|---|---|
| HPLC | High-performance liquid chromatography — separates a sample into its components by how strongly each interacts with the column. | The purity figure. Area under the main peak as a percentage of total peak area. |
| RP-HPLC | Reverse-phase HPLC. Non-polar stationary phase, polar mobile phase — the standard method for peptides. | Method matters: purity figures are only comparable when the method is. |
| MS / m/z | Mass spectrometry. Reports the mass-to-charge ratio of the ionised molecule. | Confirms identity. Without it, a purity number describes an unknown. |
| LAL | Limulus amebocyte lysate assay — detects bacterial endotoxin (LPS). | LPS confounds any cell-based or immunological assay at picogram levels. |
| EU/mg | Endotoxin units per milligram — the unit of an LAL result. | Lower is better. Look for a number, not the word "tested". |
| USP <71> | United States Pharmacopeia sterility test chapter. | A named standard, not a vague "sterile" claim. |
| TFA | Trifluoroacetic acid — the ion-pairing agent used in peptide purification. | Residual TFA affects cell viability assays. Ask for residual solvent data. |
| Net peptide content | Proportion of vial mass that is actually peptide, excluding counterion and water. | Distinct from purity. A 99% pure peptide can be 80% net peptide by mass. |
| Lyophilized | Freeze-dried under vacuum from a frozen aqueous solution. | The standard stable form for peptide shipping and storage. |
| ISO/IEC 17025 | Accreditation standard for testing and calibration laboratories. | The lab itself is audited — not just the result reported. |
| cGMP | Current Good Manufacturing Practice. | A documented, inspectable production quality system. |
| Lot / batch | A single production run with its own records and COA. | Traceability. A COA that is not lot-specific proves nothing about your vial. |
