How it works

How to test peptides for purity

What each measurement actually tells you, what a home kit can and cannot do, and how a sample becomes a certificate.

There are two honest answers to "how do I test my peptides". One is a lab: an instrument, a reference standard and an analyst, reported on a certificate. The other is a home kit, and it is worth being clear about what those can and cannot do.

What home testing kits actually tell you

Reagent and test-strip kits sold for home use detect the presence of a class of substance. They do not measure purity as a percentage, they do not confirm that a peptide is the specific sequence on the label, and they cannot tell you how many milligrams are in a vial. A colour change is not a purity figure. If the question is "is there anything here", a kit can help. If the question is "is this 5 mg of semaglutide at 98% purity", only an instrument answers it.

Testing a peptide at a lab, step by step

1. Decide what you need to know. Purity, identity and quantity answer three different questions and our standard panel reports all three. Identity asks whether the material is the compound at all. Purity asks what percentage of what is present is that compound. Quantity asks how many milligrams are in the vial against the label. Most disappointments trace to quantity, because a lyophilised cake looks identical whether it holds the labelled mass or half of it.
2. Order and pay before you ship. Build the submission in the order form, choose any add-ons, and pay. Payment first is what releases the lab address and your prepaid label — nothing is analysed, and no label is bought, before an order is paid.
3. Pack one vial per lot. Send one vial of each lot you want a certificate for. Label every vial, put the printed check-in sheet in the box, and send the lot number and the declared strength with the order. If you want several vials of the same lot compared against each other, that is the variance add-on.
4. Ship it on our rates or your own. The order form shops live USPS, UPS and FedEx rates and passes them through at cost — usually cheaper than a retail counter. You can also ship it yourself; the lab address is in your portal once the order is paid.
5. Watch it move. One scan of the check-in sheet receives the whole box. From there your portal shows the real state of the work — received, in progress, data acquired, completed — rather than an estimate.
6. Read the certificate, and let others check it. The certificate carries the result against its specification, the chromatogram, the method, the analyst who ran it and the second analyst who reviewed it. Its code and QR resolve to our own records, so anyone you show it to can confirm it is real and unaltered.

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The methods behind the numbers

• Purity and identity — HPLC-DAD. The sample is separated on a reversed-phase column and the detector records a chromatogram. Identity is confirmed by retention time against a certified reference standard; purity is reported as the compound's share of total peak area.
• Quantity. Quantified against the same certified reference standard and reported as milligrams per vial, judged against the strength your label declares.
• Sterility — USP <71>. The compendial method, with a fixed incubation that no amount of money shortens. A PCR-based rapid option is available when the timeline matters more than the compendial method.
• Endotoxin. Reported in EU/mL against a 0.5 EU/mL limit.
• Heavy metals. Reported as conforms or does not conform for lead, arsenic, cadmium and mercury.
• Residual water — Karl Fischer. Moisture in the cake, which is what drives how a lyophilised peptide holds up in storage.

How much it costs and how long it takes

$100 to $200 per sample for the standard panel, 3 business days from the day the sample arrives, rush at +100% for same or next day results. Full detail on the pricing page.

All testing is for research use only. We do not test clinical specimens and we make no statement about the suitability of any material for human or veterinary use.

Why labs and suppliers send samples here