Voltammetric Determination of Paraquat Using Graphite Pencil Electrode   Modified with Doped Polypyrrole
  Recognition and determination of paraquat (PQ) using graphite pencil electrode (GPE) modified with polypyrrole (Ppy) doped with Eriochrome blue-black B (EBB) is reported. To that end, a thin film of Ppy was deposited onto the electrode surface by electropolymerization in the presence of a functional doping ion, EBB. The Ppy/EBB-coated electrode was templated by PQ ion and then the performance of the molecularly imprinted EBB/Ppy/GPE was evaluated by voltammetric technique. The prepared electrode exhibited considerable increase in electroactivity of the sensor toward this herbicide compared to the non-imprinted electrode. To enhance the detection capability of the prepared system, the factors controlling its response were investigated and optimized using differential pulse voltammetry. The proposed analytical procedure was proved to be applicable in the concentration range of 5 to 50 {\mu}M (R^2 = 0.9939) and detection limit of (3{\sigma}) 0.22 {\mu}M. Ultimately, the proposed analytical methodology was applied to ascertain possible interferences and investigate real samples of dam water. Recovery factors were achieved between the range of 93-104%. 
Maryam Sayyahmanesh, Sara Asgari, Azam S. Emami Meibodi, Taha Mohseni   Ahooyi
physics.chem-ph