Skip to content
Technical & commercial enquiries: [email protected] Certificate of analysis issued per lot · Worldwide shipping
Register Request a quote

Reference standards for qNMR

qNMR determines content from the ratio of integrated signals, using a calibrant of known purity. It is the method of choice for assigning content to a standard in the first place, because it does not need a chromatographic response factor or a structurally related calibrant.

What this method asks of a standard

qNMR — requirements
RequirementWhy it matters
A calibrant of known purityThe result is a ratio, so the accuracy of the assigned content depends on the purity of the calibrant and on the integral ratios being well resolved.
Materials with resolved, assignable signalsqNMR needs at least one signal that is free of overlap and can be assigned unambiguously — usually a methyl or an aromatic singlet.
Identity evidenceBecause the same spectrum gives both identity and content, a certificate that carries the identity evidence and a mass-balance or qNMR assigned value is a complete basis for a calibration standard.

Standard types used with qNMR

These are the catalogue groups most often quoted for qNMR work. They are entry points into the catalogue, not a statement that any particular lot suits any particular method — that is established in your own validation, against the certificate for the lot.

Frequently asked

Why is qNMR often used to assign content to a reference standard?
It responds to every proton in the molecule rather than to a chromophore, so it does not need a response factor and can assign content to a compound for which no chromatographic standard exists. It is also insensitive to the water and residual-solvent content that complicate a mass-balance assignment.
Does a qNMR assigned value replace a purity determination?
No — the two answer different questions. qNMR gives the mass fraction of the analyte; the purity determination describes the impurity profile. Both appear on the certificate.

Related

Need a standard for a qNMR method you are validating? Send the catalogue number or the structure and the quantity you need — a technical contact answers with availability and a quotation. Request a quote.