Characterisation of non-compendial impurity reference standards


Identification and quantification of impurities in pharmaceuticals are important stages in pharmaceutical development. Impurity reference standards (IRSs) play a vital role in these stages. This paper explains the different approaches to non-compendial IRSs, with a focus on analytical characterisation. The paper will also refer to risks connected to the quantitative use of an IRS which is designed for qualitative use only, or to the use of research materials for which the assay value is grossly overestimated.