How APX Labs tests every lot.

The process, lot by lot

• 1. Lot assignment. Each production batch receives a unique lot number that is printed on every vial or pen label from that batch.
• 2. Sampling. A sample from the lot is sent to an independent analytical laboratory. APX Labs does not test its own material in-house for release.
• 3. Identity — mass spectrometry. The laboratory measures the molecular mass of the main component and compares it with the theoretical mass calculated from the expected sequence. Agreement within instrument tolerance confirms the lot is the peptide it claims to be.
• 4. Purity — RP-HPLC. Reversed-phase HPLC with UV detection separates the sample into peaks; purity is the main peak's share of total peak area. APX Labs releases lots at ≥99%.
• 5. Blends. For multi-compound pens each component is identified and quantified separately and reported on its own line.
• 6. Release. A lot that meets specification is released; the laboratory report becomes the batch COA.
• 7. Shipment. The COA for your lot ships in the box, alongside product whose label lot matches it.

What the COA shows

Lot number · test date · the laboratory's identification · RP-HPLC chromatogram, peak table and purity percentage · MS observed mass vs theoretical mass · method conditions. Reading it is covered step by step in how to read a peptide COA; the analytical methods in what HPLC/MS purity testing measures.

What testing does not cover

A COA documents identity and purity of a research reagent. It is not a safety assessment, not a sterility or endotoxin release for administration, and not a statement of suitability for any use. APX Labs products are laboratory research materials only — not for human or veterinary use, not evaluated by the FDA. Research-use policy →

Request a COA before you order

Wholesale accounts and laboratories can request the current lot's COA for any compound before purchasing. Ask on the contact page and name the compound.