Often in the USP and BP, the same method is used for assay and related substance/impurity testing.
We currently do no perform the related impurity tests routinely. It is taken for the supplier COA.
Can anyone explain the need for a resolution standard if only the assay is performed. eg. Nevirapine USP, the same method is used for assay and related substance/impurity testing. It requires a resolution solutions to perform the assay and impurities. These stds are impurity std and are very expensive. Is it necessary to run the resolution solution to check system suitability everytime we perform the assay only. I understand that it will be required when testing of related subst/impurities where we want to ensure that the method can adequately separate and quantify the impurities.
Our QA dept insists that this is necessary. I do not see the value adding if the expected resolution is more than 2, say 5.