Electrochemically Modified Sol-gel Films for Selective Heavy Metal Binding and Quantification with Total Reflection X-Ray Fluorescence

Abstract

The aim of this work is to lower limits of detection and improve selectivity of Total Reflection X-Ray Fluorescence (TXRF) for specific heavy metal ions by producing chemically selective sol-gel films. Two approaches are explored, one using chemically selective binding of Cr(VI) to pyridine functionalized sol-gel films and a second using molecularly imprinted sol-gel films for As(V) detection. Both methods are produced using electrochemically deposited sol-gel thin films on conductive ITO electrodes. These electrodes are then exposed to aqueous solutions of Cr and As which are then interfaced with a commercially available TXRF for quantification. Gold nanoparticles are incorporated to be used as an internal standard for TXRF calibrations. Sensors are regenerated for multiple uses by chemical and electrochemical means. Electrodes using a similar interface are analyzed by square wave voltammetry for analysis of Cr(VI) sol-gel interaction across a regular surface.