Tetrabutylammonium-modified clay film electrodes: Characterization and application to the detection of metal ions

This work describes the preparation and characterization of smectite clay partially exchanged with tetrabutylammonium ions (TBA+) and its subsequent deposition onto glassy carbon electrode (GCE) for application to the preconcentration electroanalysis of metal ions (Cd, Pb, and Cu). Such partial exchange of TBA+ induces the expansion of the interlayer region between the clay sheets (as ascertained by XRD) while maintaining its ion exchange capacity, which resulted in enhanced mass transport rates (as pointed out by electrochemical monitoring of permeability properties of these thin (organo)clay films on GCE). This principle was applied here to the anodic stripping square wave voltammetric analysis of metal ions after accumulation at open circuit. Among others, detection limits as low as 3.6×10−8 M for copper and 7.2×10−8 M for cadmium have been achieved.