LCZ696 Impurity 8 Catalogue L524678 CAS 1639970-62-9 M.W 365.42 M.F C22H23NO4 Specifications FAQs (2R,4S)-4-([1,1'-Biphenyl]-4-ylmethyl)-2-methyl-4-(2,5-dioxopyrrolidin-1-yl)butanoic acid