Purity and identity figures are only meaningful alongside the method that produced them. This note covers how the values are generated and what to check.
The spectrum is compared against the theoretical molecular weight of the intended structure. The useful information is the observed value, the theoretical value and the deviation between them. A result reported only as “conforms” tells a reviewer considerably less.
Purity is expressed as the area percentage of the main peak relative to total peak area at a given wavelength, typically 214 nm for peptides. Because it is an area measurement rather than a mass balance, a high figure does not by itself describe what the remaining percentage consists of.
Method conditions determine whether a purity figure is comparable between suppliers. Without them, two certificates cannot be meaningfully set side by side.
A short list that tends to separate a documented result from a claimed one.
Where an institution requires external confirmation, third-party testing can be arranged. Buyers should note that inter-laboratory variation is normal, and that a differing figure is not automatically an indication of a problem — comparison requires comparable method conditions.
A Certificate of Analysis is the starting point, not the whole file. This note sets out the documents worth requesting and the point at which to request them.
Packaging, temperature regime and documentation all affect whether material arrives in the condition it was released in — and whether it can be booked in without a query.
General laboratory notes for qualified personnel working under institutional controls. This page does not describe any procedure for administration to a living organism.
Send the catalogue reference or target sequence, required purity, quantity and destination. The procurement desk returns a formal quotation with the documentation package and lead time.