Start with the batch, not the brand
Ask whether a certificate of analysis is available for the specific batch you’d receive, not a generic one for the product line. A supplier who can immediately provide a batch-specific COA is demonstrating they actually track what they’re shipping.
Testing method and lab
Ask which lab ran the test and what method was used (HPLC is the standard for peptide purity testing). A supplier who can’t or won’t answer this is relying on the buyer not checking.
Shipping and handling
Ask how the order is packed (insulated packaging, ice packs) and what happens if a delivery is delayed in transit. A supplier with a clear answer here has clearly thought about cold-chain integrity as part of their process, not as an afterthought.
Dispatch cutoff and delivery estimate
Ask for the same-day dispatch cutoff time and a realistic delivery estimate for your postcode, rather than assuming next-day applies everywhere in the UK.
What happens if something’s wrong on arrival
Ask what the process is if a vial arrives damaged, or if the batch number on arrival doesn’t match what was promised. A supplier without a clear answer to this is one worth reconsidering before the order goes out, not after.
Reading the answers together
A single strong answer doesn’t make a supplier trustworthy on its own, and a single weak answer doesn’t automatically disqualify one either. Consistency across documentation, shipping practice, and communication is what actually separates a supplier worth ordering from repeatedly from one that isn’t.