Platinum Nanoparticles Decorated Multiwalled Carbon Nanotubes – Ionic Liquid Composite Film Coated Glassy Carbon Electrodes for Sensitive Determination of Theophylline

Platinum nanoparticles (Pt_nano) decorated multiwalled carbon nanotubes (MWCNTs)–1‐octyl‐3‐methylimidazolium hexafluorophosphate (omim]PF₆]) composite material (MWCNTs‐Pt_nano‐omim]PF₆]) was fabricated and characterized for the first time. In the presence of omim]PF₆], more Pt_nano could deposit on MWCNTs. The average diameter of the deposited Pt_nano was about 5 nm. The composite material film coated glassy carbon electrode (GCE) exhibited sensitive voltammetric response to theophylline (TP). Under the optimized conditions (i.e., preconcentration for 2 minutes on open circuit in 0.10 M pH 3.0 phosphate buffer), the anodic peak current of TP at about 1.1 V (vs. SCE) was linear to TP concentration over the range of 1.0×10^?8–1.0×10^?5 M. The detection limit was estimated to be 8.0×10^?9 M. The modified electrode was successfully applied to the determination of TP in medicine tablet and green tea. In addition, the voltammetric responses of hypoxanthine (HX), xanthine (Xan) and uric acid (UA) on the MWCNTs‐Pt_nano‐omim]PF₆]/GCE were also discussed.