Adsorption Efficiency and Partitioning Capabilty of Surfactant Monolayers on Gold

We are investigating adsorption efficiencies of sodium dodecyl sulfate (SDS) from pH 7 phosphate buffer onto polycrystalline gold substrates using electrostatics as the primary driving force via electrochemical control of the gold surface potential. It is shown through surface capacitance measurements by electrochemical impedance spectroscopy that the adsorption occurs readily. Measurement of the adsorption isotherms of SDS onto the substrate via the change in surface capacitance as a function of the bulk concentration of SDS has allowed us to determine that the minimum concentration of SDS required for efficient adsorption is below 0.011 mM. The investigation of the influence of the gold surface potential will also be presented. Further, we are probing the capability of the SDS monolayers to partition small polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. The goal of this work is to produce an electrically switchable surface for efficient pre-concentration of PAHs prior to chromatographic determination