The adsorption behavior of zinc(II) dimethyldithiocarbamate (Ziram) was studied on the surface of a poly-o-toluidine Zr(IV) phosphate nanocomposite cation exchanger. A spectrophotometric method based on the conversion of Ziram into a copper dimethyldithiocarbamate complex was applied for the study of Ziram at the maximum absorption wavelength of 437 nm. A Ziram-sensitive membrane electrode was fabricated with poly-o-toluidine Zr(IV) phosphate (an electroactive composite material). The sensitivity of Ziram for the composite cation-exchange material was monitored with potentiometric methods. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1393-1397, 2011