I have a question regarding the purchase of impurities. Method involves the testing of impurities. Specifications are "run and report". Could anyone help me in telling that from where do you purchase the impurities related to active. We will beusing USP reference standard. I am new in impurities. Sorry for the silly question but your help will be greatly appreciated.

Dear Titiana,
You can request API impurities directly from your vendor, and am sure they will help you.

thanks. Our vendoer is Sigma Aldrich. I will ask them.