Clopidogrel EP Impurity E (S-Isomer) Catalogue L620416 CAS 444728-13-6 M.W 306.81 M.F C15H15ClN2OS Specifications FAQs (S)-2-(2-chlorophenyl)-2-(6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl)acetamide