Carbon-based nanomaterials such as carbon nanotubes (CNT), carbon black and fullerenes are interesting materials for the development of analytical methods. In electrochemistry, carbon nanotubes improves the electron transfer and provides an improvement in the analytical sensitivity and selectivity of phenolic compounds determination. This book discusses several topics on analytical chemistry including enhanced electrochemical properties of multi-walled carbon nanotube paste electrode for simultaneous determination of phenolic compounds in the presence of surfactant; analytical methods for organic and inorganic toxics; bioinspired chemically modified electrodes for electroanalysis; and the adsorption properties of a new ion-selective hierarchically imprinted poly(acrylamide-co-egdma) for the extraction/preconcentration of Co(II) from an aqueous medium.