Electrochemical response of a polypyrrole-dodecylsulphate electrode with multicharged cations and vitamins B1 and B6. Application as a microsensor in flow-injection analysis

The electrochemical behaviour of multicharged cations (calcium, strontium, barium, magnesium, aluminium), and vitamins b1 and B6 at a polypyrrole-dodecylsulphate (Ppy-DDS) electrode was investigated by cyclic voltammetry. The distribution of the metal cation in the polymer was analyzed by energy-dispersive X-ray spectrometry (ED-XRS). The cyclic voltammetry results obtained show that the reduction of the polymer is accompanied by the incorporation of cations and its oxidation by the elimination of these, both processes occurring with a charge ratio QcQa = 1.2 ± 0.1. The measurements of cathodic currents were linearly proportional to the cation concentration present in the electrolyte. The ED-XRS experiment showed that the distribution of the inorganic cations inside the polymer was a function of the charge and size of the cationic species susceptible to being incorporated into the Ppy-DDS film and was explained taking in account of the electronic conduction character of the polymer. The Ppy-DDS electrode system was employed for the detection of these cations in flow-injection analysis. The detection limits (3 × std. dev. of the blank) vary between 1.0 × 10−7M for aluminium and 3.4 × 10−7M for vitamin B6. It is concluded that the electrode can be used as a sensor for the inorganic and organic cations studied.