Simultaneous determination of ascorbic acid, dopamine and uric acid using polystyrene sulfonate wrapped multiwalled carbon nanotubes bound to graphite electrode through layer-by-layer technique

A promising electrochemical system is fabricated using layer-by-layer (LBL) technique on graphite electrode, by positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged multiwalled carbon nanotubes (MWCNTs) wrapped with polystyrene sulfonate (PSS) through electrostatic interaction, for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Solubility of MWCNTs in water was increased by using linear polymer PSS. The PSS wrapped MWCNTs modified electrodes were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) and chronoamperometric techniques. The modified electrode exhibits superior electrocatalytic activity towards AA, DA and UA than the bare graphite electrode. The three separated anodic peaks were obtained at 192, 123 and 315 mV between AA–DA, DA–UA and AA–UA respectively in CV and corresponding separated anodic peaks were 210, 119 and 329 mV in DPV respectively. No electrode fouling was observed during all the experiments and good stability and reproducibility was obtained for simultaneous determination of AA, DA and UA.