Electrochemically aided solid phase microextraction: conducting polymer film material applicable for cationic analytes

Abstract

The cation uptake and release properties of a poly(pyrrole-sulfated β-cyclodextrin) (PPy-SβCD) film electrode have been investigated under both open circuit and controlled potential conditions for prospective applications in electrochemically aided solid-phase microextraction (EA SPME). The EDAX and ion chromatography results show that the K⁺ and Na⁺ cation uptake is enhanced if a small negative potential is applied to the electrode in the range where PPy is in its neutral form. These cations are released rapidly from the film if the applied potential is switched to the value at which PPy is converted to its positively charged form, i.e., oxidized state. The cation ingress and egress mechanism is affected both by the cation exchange at the negative sulfate moiety on the cyclodextrin sites and electrostatic interactions generated by the applied potential. The electrochemical "switching" capability increases the speed of the cation uptake and release, presumably due to electro migration, as compared to the open circuit ion exchange which is controlled solely by diffusion. Our preliminary fundamental results show that the PPy-SβCD film is suitable for the future design of EA SPME devices.