A thin film composite membrane including a porous support and a thin film polyamide layer characterized by having a dissociated carboxylate content of at least 0.45 moles/kg at pH 9.5 and a method for making a composite polyamide applying a polar solution comprising a polyfunctional amine monomer and a non-polar solution comprising a polyfunctional amine-reactive monomer to a surface of the porous support and interfacially polymerizing the monomers to form a thin film polyamide layer, wherein the method is characterized by the non-polar solution comprising at least 0.025 wt% of an acid compound including at least one carboxylic acid moiety and at least one amine-reactive moiety selected from acyl halide and anhydride.