Two RFQs for 'a 20-mer at 98%' can produce quotations that differ by a factor of several, because the brief leaves the expensive variables undefined. Writing them down at the start is cheaper than renegotiating after a method has been developed.
Molecule definition
State the full sequence, the N- and C-terminal modifications, any non-standard residues, labels or conjugations, and the salt form you expect (for example acetate versus trifluoroacetate). State whether the counter-ion matters for your downstream use, because it changes both the purification route and the net peptide content you weigh.
Quantity and intended use
Give the screening quantity and the likely repeat volume separately. A 100 mg screen and a 1 kg repeat order are different commercial propositions: purification strategy, solvent handling, release testing and pack format all change with scale. State the intended use so the documentation scope can be set correctly from the start.
Quality definition
Specify the purity window, the HPLC method (column, gradient, detection wavelength, integration rules) and whether the figure is area normalisation or an external-standard assay. State the identity method, which related substances carry individual limits, and the reporting threshold. Agree the water and residual solvent limits and their methods too.
Documentation and logistics
List the required documents (COA, MSDS, TDS, chromatograms, MS trace, elemental impurities, microbiology where applicable), the pack size and label format, the destination country and any import requirements. Ask how a specification or method change will be handled on repeat orders.
Send us your sequence and intended volume and we will return a line-by-line brief with the open questions marked, so the quotation you receive is comparable with any other.