A method for preparing ammonium tetrakis(pentafluorophenyl)borate salt comprising reacting a secondary amine with an aldehyde to form an iminium ion; hydrogenating the iminium ion by reaction with a reducing agent to form a tertiary amine; reacting the tertiary amine with a mineral acid to form an amine salt; and reacting the amine salt with K[B(C6F5)4], Li[B(C6F5)4], or combinations thereof to form an ammonium tetrakis(pentafluorophenyl)borate salt, wherein the secondary amine is derived from a non-animal source and the aldehyde has seven or more carbon atoms; wherein the ammonium tetrakis(pentafluorophenyl)borate salt is characterized by a solubility at 25° C. in hexane, cyclohexane or methylcyclohexane of at least 10 weight percent; and wherein the tertiary amine has a molecular weight of at least 450 g/mole is provided.