A NOVEL INSOLUBLE POLYMERIC DIAZONIUM SALT COLOR DEVELOPER CONSISTING OF A DIAZOTIZED AROMATIC POLYAMINE BOUND BY AN AMIDE LINKAGE TO A CATION EXCHANGE RESIN CAN BE PREPARED BY REACTING A CATION EXCHANGE RESIN CONTAINING ACID GROUPS WITH A HALOGENATING AGENT TO CONVERT SOME OF THE RESIN ACID GROUPS TO ACYL HALIDE GROUPS, REACTING THE RESULTING ACYL HALIDE GROUPS WITH AN AROMATIC POLYAMINE TO FORM A RESIN CONTAINING AMIDE LINKAGES AND FREE AROMATIC AMINO GROUPS, AND THEN DIAZOTIZING THE FREE AROMATIC AMINO GROUPS. THE RESULTING INSOLUBLE COLOR DEVELOPER CAN BE USED TO DETECT COUPLING COMPOUNDS BY FORMING COLORED REACTION PRODUCTS WITH SUCH COUPLING COMPOUNDS. THE COLOR DEVELOPER CAN ALSO BE USED TO DETECT AN ENZYME SYSTEM WHEREIN THE ENZYME CATALYZES A REACTION WITH A SUITABLE SUBSTRATE TO RELEASE A COUPLING COMPOUND WHICH WILL FORM A COLORED REACTION PRODUCT WITH THE INSOLUBLE COLOR DEVELOPER.