Peptide purity vs peptide content: what buyers should compare

A percentage needs a definition

Two documents can use the word “purity” while reporting different measurements. In a typical peptide HPLC assessment, the main peak area is compared with the integrated areas detected by the method. That result is not automatically the fraction of the entire vial contents represented by the target peptide.

Reference: Bachem: peptide content and concentration calculator

Content and labelled mass need their own basis

A lyophilised material can include peptide, moisture and counterions. Content or assay information helps describe the amount represented by peptide; the exact definition and calculation basis should be taken from the issuing laboratory’s documentation. Different suppliers may use different terminology.

Bachem’s calculator illustrates the distinction by using gross weight, purity and assay as separate inputs. Do not transfer that calculation to a report without first confirming what its measurements mean.

Reference: Bachem: peptide content and concentration calculator

Compare like-for-like quotations

A useful comparison sheet has separate columns for the catalogue specification, pack quantity, price and documentation basis. Keep a missing measurement marked as unconfirmed rather than replacing it with an assumption.

• Is the quoted mass a nominal label claim or a measured result?
• What does the reported purity percentage measure?
• Is content or assay reported separately, and how is it defined?
• Are the chemical form, batch and test methods identified?
• Do both quotations use the same pack and currency basis?

How to read Holy Water’s catalogue quantities

Holy Water catalogue prices are in USD per box of 10 vials. The smaller per-vial amount is the box price divided by 10; it is a comparison figure, and orders are for whole boxes.

The catalogue specification identifies the variant requested. It does not replace a batch measurement. If your procurement requires a particular assay, mass basis or analytical threshold, put that requirement in the quotation request so it can be assessed with the available documents.