A certificate of analysis (COA) is the only document that tells you what is actually in a vial. Most researchers glance at the purity number and move on. That one number answers less than you think. Here is how to read the whole report in about two minutes.
1. Match the lot number
Every vial and every report should carry the same lot number. A COA without a lot number, or one that covers a different lot or a different vial size, tells you nothing about the vial in your hand. At Nyxo, every lot carries an ML number (for example ML-005), and that number is printed on the vial label and on the report.
2. Check the lab and verify the report
Look for the testing lab’s name, the date tested and a report or accession ID. A good lab lets you confirm the report on its own site with that ID or a verification code. If there is no way to confirm the report independently, treat it as a claim, not evidence.
3. Purity by HPLC
HPLC purity is the share of the signal that comes from the target compound, usually read by UV at 214 or 220 nm. A result of 99% means 99% of the detected material is the main peak. Look for the chromatogram itself, not just the number: one dominant peak with small, separated minor peaks is what a clean result looks like.
4. Identity by mass spectrometry
Purity says the sample is mostly one thing. Mass spectrometry says which thing. The report should show an observed mass that matches the compound’s expected mass. A high purity result paired with the wrong mass means you have a very pure sample of the wrong compound.
5. Net peptide content
Purity and quantity are different questions. A vial can be 99% pure and still hold less peptide than the label says, because lyophilized peptides also contain water and counter-ions. Net content reports the actual milligrams in the vial. Expect it to be at or above the label amount.
6. Contaminant screens
A full panel goes beyond purity and identity:
- Endotoxin — bacterial residue, measured by LAL assay.
- Microbial screens — checks for microbial contamination where the lab ran them.
- Heavy metals — usually measured by ICP-MS.
Many suppliers test purity only. Ask for the rest.
Red flags
- No lot number, or the same report reused across many lots.
- No test date, or a date long before the product was made.
- A lab you cannot find or contact, or no way to verify the report.
- A purity number with no chromatogram and no mass result.
- Identical results on every lot. Real lots vary.
A real example
Nyxo lot ML-005, GHK-Cu 100 mg, was tested by Kovera on a six-assay panel: HPLC purity 99.547%, identity confirmed, and 106.12 mg net content against a 100 mg label. Report KVR-2026-6C292F. Every Nyxo lot report is published on our certificates page, matched by lot number.
All Nyxo products are for laboratory research use only. Not for human or animal use.