[OscarDiggs]

Quick disclosure up front: I rep for Vyal Labs, a research peptide supplier. The site operator asked me to keep this section educational, so that is what this is – a practical walkthrough of COA verification that applies to any vendor, us included. Everything we sell is RUO (research use only).

What a trustworthy COA actually looks like:

1. Batch-matched, not recycled. The lot number on the COA should match the lot number on the vial you receive. A vendor PDF with no lot number, or one lot number that never changes across months of orders, is a red flag. Ask the vendor how you can look up the COA for YOUR specific lot before you order.

2. Named third-party lab. The report should name an independent analytical lab with a real location you can verify. “In-house tested” means nothing. For transparency: our batches are tested by Accurate Test Labs in Fort Lauderdale, FL, and the reports carry their name.

3. HPLC purity AND measured content. Purity (e.g. 98.9%) tells you how much of the material is the target peptide vs. impurities. Measured content tells you how much actual peptide mass is in the vial vs. the label claim. A report that only shows purity is half the picture – a vial can be 99% pure and still be underfilled.

4. Heavy metals panel. Look for arsenic, cadmium, lead, and mercury at minimum, with actual results (“Not Detected” or a number), not a blank field. Not every vendor runs metals on every batch – it is fair to ask which batches have it.

5. What HPLC does and doesn’t show. HPLC is the standard purity method for peptides. It does not confirm sequence identity the way mass spec does. If a vendor claims MS data, ask them to show it on the report.

How to use this: before trusting any vendor’s paperwork, ask four questions – Is the COA batch-matched? Which lab ran it? Does it show measured content, not just purity? Can I look up the COA for my lot myself? A vendor who answers all four cleanly is doing it right.

Happy to answer questions on reading reports – that is why I am here.

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