De-bundled single-walled carbon nanotube-modified sensors for simultaneous differential pulse voltammetric determination of ascorbic acid, dopamine, and uric acidElectronic supplementary information (ESI) available: DPV results at different pH, and with different ratios and different concentrations. See DOI: 10.1039/c7nj04371f

• Main Authors: Thirumalai, Dinakaran, Subramani, Devaraju, Yoon, Jang-Hee, Lee, Jaewon, Paik, Hyun-jong, Chang, Seung-Cheol
• Format: Article
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c7nj04371f

A new approach based on differential pulse voltammetry (DPV) was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using a modified glassy carbon electrode (GCE). The sensor was constructed by a simple "one-step" technique, wherein de-bundled single-walled carbon nanotubes (SWCNTs) were drop-cast onto the GCE. Without de-bundling, the SWCNTs were poorly dispersed in aqueous solution and were ineffective for the one-step procedure. De-bundling of the SWCNTs was achieved using a small amount (0.1 wt%) of the synthesized polymer dispersant, sulfonated poly(ether sulfone) (SPES); the de-bundled SWCNTs had a high aspect ratio (length = 2.5 ± 1.0 μm; height = 2 ± 1 nm, as determined using transmission electron microscopy and atomic force microscopy). The de-bundled SWCNTs also led to enhanced electrocatalytic activity and selectivity of the modified sensor for the simultaneous determination of AA, DA, and UA in DPV measurements: the peak-to-peak separation values were 221, 119, and 340 mV ( vs. Ag/AgCl) for DA-AA, UA-DA, and AA-UA, respectively. The dynamic linear ranges for AA, DA, and UA were 0.2-1.6 mM, 5.0-50 μM, and 5.0-60 μM, and the detection limits were 10.6 μM, 15 nM, and 113 nM (S/N = 3), respectively. The analytical performance of the developed sensor was demonstrated in the determination of AA and DA in commercial pharmaceutical samples (vitamin C tablets and DA injection). The characteristics of the modified sensor make it promising for the individual or simultaneous determination of AA, DA, and UA. De-bundled SWCNTs modified glassy carbon electrode for the simultaneous differential pulse voltammetric determination of ascorbic acid, dopamine, and uric acid.