When you receive a research peptide order, certain documentation should accompany what you have paid for. This is not a matter of going above and beyond — it is a baseline expectation for any supplier operating seriously in this space. This guide covers what documentation to expect, what each document contains, and what to do if anything is incomplete.
The Certificate of Analysis: your primary quality document
A Certificate of Analysis (CoA) is the document that allows you to verify that the product you received matches the product you ordered. It should be batch-specific (linked to the exact lot number of the stock dispatched), not a generic specification document that could apply to any batch of the compound. A CoA that does not reference a batch number cannot be verified as applying to your specific order.
At minimum, a CoA for a research peptide should include: the product name and lot/batch number; the analytical purity result expressed as a percentage; the method used to determine purity (e.g. RP-HPLC at 214nm); an identity confirmation (typically the observed molecular weight from mass spectrometry compared to the theoretical value); the appearance of the product; and storage conditions.
Molecular data and product specifications
In addition to the CoA, a supplier should make basic molecular data readily accessible for every product. This includes the molecular formula, molecular weight (theoretical), CAS number (where applicable), and storage conditions. This data allows you to cross-reference the compound independently — for example, by verifying the theoretical molecular weight against publicly available databases such as PubChem or the NCBI protein database.
Nexapep lists all available molecular data on each product page. This information is included as a standard reference for researchers and is derived from verified chemical databases. If you notice a discrepancy between listed data and an external reference, please contact us.
Storage and handling guidance
Every research peptide should come with explicit storage guidance. For lyophilised peptides, this is typically: store at -20°C for long-term preservation; store at 2-8°C after reconstitution; do not freeze reconstituted peptide. This guidance should be clearly stated on the product vial label, on the product page, and in accompanying documentation. Storage guidance is not an optional extra — it is a requirement for a product described as research-grade.
RUO labelling and what it means
All Nexapep products carry a clear "Research Use Only" (RUO) designation. This is not legal boilerplate appended after the fact — it is the actual supply classification under which the product is sold and the condition under which it may be supplied without medicines licensing. Products supplied under RUO classification are not intended for human or veterinary consumption, and must be used only in appropriate laboratory research settings by qualified researchers.
If you receive a peptide from any supplier without clear RUO labelling, or if a supplier's product descriptions or communications imply or suggest human use, this represents a departure from the framework under which the product should be supplied. It should be treated as a risk factor both for regulatory compliance and for product quality (suppliers who are careless about compliance obligations often exhibit the same carelessness about quality standards).
Receipt inspection: what to do when your order arrives
On receipt, inspect each vial before placing in storage: the lyophilised content should appear as a white to off-white powder or intact cake; the vial should be sealed and undamaged; a slight vacuum may be detectable when pressing the stopper (this is normal and desirable). Note the lot number from the vial label and cross-reference with your CoA. Record the receipt date in your research records. If anything appears abnormal, photograph the vial and contact the supplier before opening.
If documentation is missing or incomplete
Contact hello@nexapep.co.uk with your order number and the specific documentation you require. Include the product name and lot number from your vial label if known. We aim to respond to all documentation requests within one business day and will provide the relevant documentation for your batch. If you have received a product from us and the CoA you received does not match the lot number on your vial, flag this immediately and we will investigate and resolve it.