Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid

• Published in: Materials Science & Engineering C 2014-11, Vol.44, p.58-68
• Main Authors: Afraz, Ahmadreza, Rafati, Amir Abbas, Najafi, Mojgan
• Format: Article
• Language: English
• Subjects: Ascorbic Acid - blood; Ascorbic Acid - urine; Biosensing Techniques; Carbon paste electrode; Dielectric Spectroscopy; Dopamine - blood; Dopamine - urine; Electrochemical Techniques; Electrodes; Gold - chemistry; Gold nanostructure; Humans; Ionic liquid; Ionic Liquids - chemistry; Metal Nanoparticles - chemistry; Microscopy, Electron, Scanning; Multiwalled carbon nanotube; Nanotubes, Carbon - chemistry; Oxidation-Reduction; Spectrometry, X-Ray Emission; Uric Acid - blood; Uric Acid - urine; X-Ray Diffraction
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2014.07.065

We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450μM, respectively, and with 120, 30 and 30nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. [Display omitted] •New method for simultaneous determination of AA, DA and UA was developed.•MWCNT/ionic liquid/cauliflower-like Au nanostructure was used for CPE modification.•Optimization of electrode composition was done by Design-Expert software.•The pH effect, peak separation mechanism and real samples was thoroughly studied.