Anastrozole EP impurity B

Chemical Name: (2RS)-2,3-bis[3-(1-cyano-1-methylethyl)-5-(1H-1,2,4-triazol-1-ylmethyl)phenyl]-2-methylpropanenitrile (as per EP) ; 2,3-Bis(3-(1-cyano-1-methylethyl)-5-(1H-1,2,4-triazol-1-ylmethyl)phenyl)-2-methylpropionitrile (as per USP)