How To Choose A Reliable Peptide Supplier

If you're sourcing peptides internationally, one of the first questions is whether your supplier can consistently deliver the same purity every time. That matters more than price.

Check The QC Data, Not Just The COA Number

Ask for actual HPLC chromatograms and MS spectra from a recent batch similar to yours. A COA that says ">98%" without supporting data is just a number on paper.

Evaluate Communication Response Time

Send a test inquiry with a moderately complex sequence. If they respond in 24 hours with a realistic timeline and potential concerns about your sequence, that's a good sign. Vague "no problem" answers without technical review are a red flag.

Ask About Difficult Sequence Experience

Sequences with multiple consecutive hydrophobic residues, Cys pairs, or D-amino acids require specific strategies. A supplier who can explain their approach (pseudoproline, Dmb, specialized resins) has real synthesis experience.

Verify Shipping Track Record

Ask which countries they ship to regularly and whether they handle cold-chain requirements. Export experience matters — especially for modified peptides that need temperature control.