slug: how-to-read-a-coa title: How to read a certificate of analysis — field by field excerpt: A COA is a compact document, but every field carries weight in a regulated research workflow. Here's what each one means and what to do when a field is vague or missing. publishedAt: 2026-04-08T12:00:00.000Z tags: ['method', 'documentation'] author: elev8 Labs
A certificate of analysis (COA) looks simple. One page, a handful of fields, a number or two that seem to matter, and a signature. For a researcher operating under any kind of documentation burden — ISO adjacency, GLP, institutional review, journal reviewer — every one of those fields matters.
This note walks through the fields that appear on a typical analytical COA for a reference peptide, what each one signals, and what to look for when a field is soft or absent.
Product description
Usually the first field on the document. Should include the peptide's accepted research name and its physical form (lyophilized, solution, etc.). A good COA also cross-references the molecular weight and molecular formula.
Soft signals: purely marketing names, no molecular information, no form description. These often indicate the COA was generated by the vendor's order-management system, not by the analytical lab.
Lot number
The most important field on the document. Every other field on the COA is a claim about this specific lot. If your vial says EL8-L-7221 and the COA says EL8-L-7217, the COA does not describe your material. Full stop.
Soft signals: "batch" instead of "lot" (sometimes used interchangeably, sometimes not — ask), missing lot references, or a lot number that does not match the physical vial.
Purity
Reported as a percentage, usually against an analytical method (HPLC). A good COA names the method explicitly: "Purity ≥ 98.0% by RP-HPLC, UV 214 nm."
- "≥ X%" — lower-bound claim the vendor is willing to stand behind.
- "X.X%" — specific measured value from the assay.
- "typical" — soft claim. Ask for the lot-specific value.
The difference between 98% and 99% may seem trivial, but for method development the absolute purity affects downstream calculations. Know your threshold.
Analytical method
This is where many low-tier COAs become vague. A research-grade document names:
- The chromatographic method (RP-HPLC, HPLC-MS, etc.)
- The detection method (UV 214 nm, UV 280 nm, ELSD, etc.)
- The column specifics (sometimes — optional but good)
- The mobile phase or gradient summary
Red flag: a blank method field, or just "HPLC" with no detector. These are unusable in a regulated audit.
Identity
Identity confirmation is typically by ESI-MS (electrospray ionization mass spectrometry). The COA should either report the observed m/z value or state "ESI-MS: consistent with expected mass." A well-formed COA includes both.
If identity is stated as "by visual inspection," the document is not a COA. It is a shipping memo.
Appearance
"White to off-white powder." "Clear colorless solution." This field sets expectations so you can flag gross physical anomalies before reconstituting a sample. If the vial does not match the description on the COA, open a ticket immediately.
Solvent / reconstitution
Appears on COAs for peptides that ship in solution or have a recommended reconstitution protocol for analytical use. This field is not a dosing or use-of-product instruction — it describes how the reference material should be handled in a laboratory context.
Date of analysis
The assay was run on this date. Establishes a clock for the lot's age and any stability considerations.
Analyst / signatory
The person (or in some cases, the analytical lab) who performed the analysis and attests to the numbers. A signed COA is a stronger document than an unsigned one — it commits the analyst to the claim.
Red flag: unsigned COA, or "signed by QC" with no individual attribution. Depending on the downstream audit, this may be insufficient.
What we include
Our COAs are written to carry everything above, plus the lot-level traceability link back to our shipment record. If a downstream researcher pulls up an old sample and wants to confirm the COA, we can retrieve the signed document by lot number for the retention period documented in our internal records.
When a COA raises questions
Email support@elev8labsrx.com with the lot number. We will either clarify the field in question or pull the source document from the analytical lab. COAs are paperwork; their value is that they are answerable.
elev8 Labs products are reference standards for laboratory research only. Not for human consumption.