Electrochemically aided control of solid phase micro-extraction (EASPME) using conducting polymer-coated solid substrates applicable to neutral analytes

A method for the extraction and selective determination of the neutral species arsenobetaine (AsB) is proposed using electro-synthesized organic conducting polymer (OCP) films. The polymer films are used as solid phase micro-extraction (SPME) elements for the direct and specific extraction of trace levels of AsB. The separation and detection of the arsenic (As) species is attained using an HPLC-ICP-MS interfaced system. The selectivity of the method towards neutral AsB in the presence of other anionic As-species is explained in terms of the change in the hydrophobic nature of the film during the doping/undoping processes. The type of OCP, the thickness of the film, the applied potential during uptake and release of AsB are among the factors studied for the method. The uptake and release time/potential profiles are given, and a thermodynamic model is proposed. The performance of poly(3-octylthiophene), poly(3-dodecylthiophene), and poly(3-hexadecylthiophene) films were compared, with the best results obtained using poly(3-octylthiophene). The detection limit and linear dynamic range using this method are 14 ng mL(-1) and 70-1200 ng mL(-1), respectively. The method was validated using a standard reference material and tested for the determination of AsB in artificial environmental soil samples.