Requesting a custom peptide synthesis quote: the specification sheet to send

Why a specification beats a sequence in an email

A quote is only comparable if every vendor priced the same thing. Send one sequence and a quantity and each vendor fills the gaps with its own defaults: one includes a counter-ion exchange, another quotes crude, a third leaves amino acid analysis out. ICH Q7 defines a specification as a list of tests, references to analytical procedures and acceptance criteria that material must meet to be acceptable. [1] Writing one before you ask for quotes turns a vague request into a document you can check the delivery against.

Vendor pages below were read on 30 October 2026. Prices are list examples, not quotes, and we did not request quotes ourselves.

The fill-in specification sheet

Copy these fields into your request. Where a field is blank, the vendor decides for you.

• Project name and your internal reference.
• Sequence, one-letter code, written N-terminus to C-terminus (Biosynth's form asks for NH2 to COOH). [2]
• Length in residues (check it matches the sequence).
• N-terminal modification (for example free amine or acetyl) and C-terminal modification (for example free acid or amide); Biosynth's form has a separate field for each. [2]
• Internal modifications by position: disulfide bridges with the paired residues, cyclisation type, phosphorylation sites, labels, non-natural residues.
• Conjugation, if any (for example KLH, BSA or OVA carrier proteins, as listed on Biosynth's form). [2]
• Net quantity in milligrams, and whether that is gross weight or peptide content.
• Purity target by HPLC, with the method or wavelength if you need it fixed.
• Counter-ion or salt form: default, acetate or chloride exchange, and the residual limit you will accept.
• Analyses to report: HPLC chromatogram, mass spectrum, amino acid analysis, water content, endotoxin, counter-ion content, solubility.
• Delivery format: lyophilised in one vial or aliquoted, vial count and amount per vial.
• Documents: lot-specific certificate of analysis naming the testing site, raw chromatogram and spectrum files, SDS.
• Required-by date and shipping conditions.

How each choice moves price and lead time

Purity. Boster Bio's 5 mg per-residue ladder rises from USD 3.50 for crude (over 40 percent) to USD 15.50 for over 98 percent, with stated turnaround lengthening from 5-7 to 18-21 days; the full ladder and LifeTein's 20-mer examples are in the site's custom-versus-catalog cost guide. [3] [4] The practical point for a quote request is to state the purity tier explicitly, because it is the largest single price lever.

Modifications. LifeTein lists USD 200 for one disulfide bridge, USD 400 for two, USD 500 for amide cyclisation and USD 100 per phosphorylation site on a 20-mer. [4] Boster Bio says it offers over 200 modifications, with charges for special modifications quoted individually. [3] Name each modification by position so every vendor prices the same structure.

Analyses and counter-ion. Biosynth's quote form lists solubility testing, amino acid analysis, endotoxin testing, chloride salt-form exchange and acetate counter-ion as optional reports with additional fees. [2] Boster Bio lists endotoxin, counter-ion, Karl Fischer water content and optical rotation as add-ons without published prices. [3] LifeTein says MS, HPLC and a certificate are provided for all synthetic peptides. [4] Ask for each optional analysis as a separate priced line.

Lead time. LifeTein gives 1-2 weeks for rush unpurified peptides and 2-3 weeks for purified ones, while a banner on the same page says 3-5 days for crude peptides. [4] Pages disagree with themselves, so ask for the lead time per option in writing, not one number for the order.

Testing uses up product: size the order for it

Biosynth's analytical services page recommends at least 0.5 mg of lyophilised peptide for amino acid analysis, 0.2 to 0.5 mg for HPLC and at least 0.1 mg for mass spectrometry. [5] Those are its sample sizes for its own service, but the point carries over: if you plan to re-test on receipt, a 1 mg order can lose most of its mass to verification. Add the material you will consume in testing to the net quantity before you ask for a quote, or ask the vendor to ship a separate retained sample.

Worked comparison of two specifications

Specification 1: 15-mer, free ends, 5 mg, over 80 percent, vendor default salt, HPLC and MS only. On Boster Bio's ladder that is 15 x USD 6.50 = USD 97.50 with a 10-12 day turnaround. [3]

Specification 2: the same sequence at over 95 percent with amino acid analysis and an acetate exchange. Synthesis alone is 15 x USD 11.50 = USD 172.50 at 15-18 days, before the analysis and exchange, which are quote-only on the pages we read. [2] [3]

For a 20-mer with one disulfide bridge at over 95 percent, LifeTein's published examples add to USD 200 plus USD 200, or USD 400, at 1-4 mg. [4] Treat these as a check on whether quotes are in the expected range, not as a price you will be charged.

Reading the quote that comes back

Check that the quote repeats your sequence and modifications exactly, states whether quantity is gross or net, names the purity method, lists each analysis you asked for with its price, and says what documents ship with the lot. Anything you asked for that is missing from the quote is not included. Then compare the delivered certificate against your specification line by line, as described in the site's certificate-reading guides.