Most peptide suppliers will quote any sequence at any purity. That is not a service, it is a price list. The useful question is whether the supplier will tell you what your sequence should be supplied as — because a peptide that is correct at 95% for a screen is not correct for a binding assay, and the difference shows up as a failed experiment rather than a complaint.
1. Send the specification, not just the sequence
To quote accurately we need:
- The full amino acid sequence, or the CAS number if you have one
- Application — screening, receptor binding, cell culture, structural work, stability study
- Purity target and whether you need the raw chromatogram or mass spectrometry confirmation
- Counter-ion preference — TFA, acetate or HCl. If you have no preference, we will recommend one and explain why
- Modification — PEGylation, cyclisation, lipidation, or a specific terminal cap
- Quantity and pack format — single vial, kit with bacteriostatic water and syringes, or bulk
- Delivery destination, so we can quote on the incoterm you want
Our guide to writing a peptide RFQ covers how to structure an enquiry so quotes come back comparable.
2. What feasibility review adds
Some sequences are straightforward, some are not. A long or highly hydrophobic sequence, a sequence with multiple cysteine residues, an unusual post-translational modification or a very high-mass construct will carry a different risk profile on synthesis and purification.
We flag these before you commit, because a peptide that fails on resin cleavage costs far more in time than a conversation at RFQ stage. Where a different synthetic route would produce a better result, we say so and explain the trade-off.
3. Purity grades, and what each is for
| Grade | Specification | Typical use |
|---|---|---|
| Standard | ≥95% HPLC by area, identity by HPLC retention time, batch COA with chromatogram | First-pass screening, assay development, general research |
| Verified | ≥98% HPLC by area, peptide content stated, counter-ion stated, mass spectrometry on every lot | Binding and functional assays, cell culture work, anything where a failed batch costs a week |
| Characterised | ≥99% HPLC, MS, endotoxin, residual solvents, water content, amino acid analysis, stability data | Institutional buyers, GMP-adjacent programmes, regulatory submission support |
There is no free version of characterisation. If a quote looks like the Standard grade at Characterised prices, ask what was actually run.
4. Modifications and custom formats
We can quote synthesis for PEGylated constructs, cyclic and side-chain cyclised peptides, biotinylated and fluorescently labelled variants, and terminal acetyl or amide capping. For kits we can specify bacteriostatic water or sterile water, syringe sizes including 40 IU and 100 IU insulin syringes, and a per-vial or multi-vial format.
Our peptide dosage calculator works out reconstitution volume and syringe dose for any vial — useful when you are planning a kit for a team rather than for yourself.
5. Lead time and what it depends on
Synthesis, purification and characterisation typically run 10–18 working days for a standard sequence, and longer for a heavily modified or very long construct. Characterisation adds several days because the analytical work is sequential, not parallel — which is exactly why a bulk order with the full characterisation pack quoted at Standard pricing is worth questioning.
6. Custom synthesis versus catalogue
For 28 of the sequences we stock as catalogue SKUs — the growth factor class, the cognitive class, the metabolic class and the reference standards — there is no reason to synthesise. You get a shorter lead time, a lower price and a lot COA that already exists.
Custom synthesis earns its place when the sequence is not on the catalogue, when you need a specific counter-ion or modification, or when you want a peptide content or stability specification the catalogue grade does not carry. Browse the catalogue first, and ask us for custom only where it is genuinely the better route.
7. What you get back
- A formal quotation with unit price, quantity breaks, lead time and price validity
- A recommended grade with the reasoning
- An analytical specification listing every test to be performed
- The document pack listed on our export documentation page
Quotations normally return within one business day of a complete enquiry. Send the specification and the trade desk will take it from there.
B2B trade only — request a quote
All peptides are research-grade, for in-vitro use only, and supplied against a valid drug licence. Tell us your sequence, quantity and destination and the trade desk will respond within one business day.