Electroanalytical chemistry with zeolites

In this paper we explore how solution phase molecules affect the electrochemistry of silver-cation exchanged zeolite-modified electrodes (ZMEs). Furthermore, we examine the potential utility of ZME response to quantify solution phase analytes in aqueous and non-aqueous solutions. We give several examples which show that ZMEs are useful in assessing detection efficiencies and analyte selectivities. However, flow systems are better if one desires incorporation into a device. A useful method is to place the zeolite in a conventional HPLC column coupled to a conventional thin-layer amperometric electrochemical detector. The detection method described in this paper is based upon suppressed electroactivity of intra-zeolite silver cations. Indirect analyte detection occurs where the analyte accelerates the departure of silver ions into the solution phase, whereupon they are electrochemically determined. 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 alkali metal cations, benzene, trichloroethylene and water are described.