Electroanalytical chemistry with zeolites

In this paper we explore how solution phase molecules affect the electroche mistry of silver-cation exchanged zeolite-modified electrodes (ZMEs). Furth ermore, we examine the potential utility of ZME response to quantify soluti on phase analytes in aqueous and non-aqueous solutions. We give several exa mples which show that ZMEs are useful in assessing detection efficiencies a nd analyte selectivities, However, flow systems are better if one desires i ncorporation into a device. A useful method is to place the zeolite in a co nventional HPLC column coupled to a conventional thin-layer amperometric el ectrochemical detector. The detection method described in this paper is bas ed upon suppressed electroactivity of intra-zeolite silver cations. Indirec t analyte detection occurs where the analyte accelerates the departure of s ilver ions into the solution phase, whereupon they are electrochemically de termined. We show examples where promotion of silver in the solution phase occurs, via both analyte-silver interactions, and interactions between the supporting electrolyte and the analyte. Amperometric determinations of alka li metal cations, benzene, trichloroethylene and water are described. (C) 1 999 Elsevier Science B.V. All rights reserved.