A reservoir type of optode is described for simultaneous and remote determination of Cd and Zn using [9-(1',4',7', 10',13'-pentaazacyclopentadecyl)methylanthracene] as the fluorophore. Simultaneous analysis was achieved by the significant perturbation in the fluorescence spectrum of the Cd-ligand complex while the Zn complex only results in enhancement in the fluorescence intensity as compared to ligand alone. The ion permeability of several membranes were examined; Nafion and cellophane were used for the construction of the optode. Using the optode constructed with cellophane, for 20 min immersion time, the 3-s detection limits were found to be 4.5 mu g l(-1) for Cd and 0.6 mu g l(-1) for Zn. (C) 2000 Elsevier Science B.V. All rights reserved.