Linagliptin Impurity E Catalogue L562376 CAS 1446263-38-2 M.W 472.54 M.F C25H28N8O2 Specifications FAQs (R)-7-(but-2-yn-1-yl)-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-8-(piperidin-3-ylamino)-1H-purine-2,6(3H,7H)-dione