How to choose analytical reference standards

What is the checklist for selecting accurate analytical reference standards in a chemical testing lab?
As a starting point, there are three questions before selecting it

  1. If you are working according to the monograph method or if you are using your in-house method?
  2. If you are looking at an API or an impurity?
  3. Do you want to identify the API or do you want to quantify it?

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