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Author: search.filters.author.Puangjan, ApinyaSubject: search.filters.subject.Ascorbic acid

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    Application of functionalized multi-walled carbon nanotubes supporting cuprous oxide and silver oxide composite catalyst on copper substrate for simultaneous detection of vitamin B2, vitamin B6 and ascorbic acid
    (2017-07-01)
    Puangjan, Apinya
    ;
    Chaiyasith, Suwan
    ;
    Taweeporngitgul, Wipawee
    ;
    Keawtep, Jeerunda
    A new electrochemical sensor was fabricated from chemically functionalized multiwall carbon nanotubes and electrochemically deposited cuprous oxide and silver oxide composite over the nanotubes on copper substrate. The structural, functional, morphological, electrical properties and elemental composition of the composite were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy, field transmission electron microscopy, electrochemical impedance spectroscopy and energy dispersive X-ray spectroscopy. The developed sensor exhibited excellent electrochemical catalytic activity toward oxidation of vitamin B<inf>2</inf> (VB<inf>2</inf>), ascorbic acid (AA) and vitamin B<inf>6</inf> (VB<inf>6</inf>). Compared to the performance of simple copper substrate, that of the modified electrode was greatly superior. This can be attributed to its robust structure, excellent conductivity and large surface area. With a simple electrode that relies on linear diffusion at the surface, an electrochemical analytical method may have a selectivity problem, i.e., various species present in the target medium may oxidize or reduce at potentials not very different from each other. The conducting porous layer of our modified electrode alters this diffusion characteristic to one of approximately ‘thin layer’ that facilitates better discrimination between species. In this work, differential pulse voltammetry was used for simultaneous determination of VB<inf>2</inf>, AA and VB<inf>6</inf>. The linear ranges were 0.05–1752.65 μM, 0.05–1628.54 μM and 0.02–1056.12 μM, and the detection limits (S/N = 3) were 0.014 μM, 0.011 μM and 0.008 μM, respectively. In addition to its high performance, this inexpensive sensor is perfectly stable for simultaneous determination of these species in real samples.
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    Electrochemical sensor based on PANI/MnO2-Sb2O3 nanocomposite for selective simultaneous voltammetric determination of ascorbic acid and acetylsalicylic acid
    (2016-12-01)
    Puangjan, Apinya
    ;
    Chaiyasith, Suwan
    ;
    Wichitpanya, Saniporn
    ;
    Daengduang, Sirirat
    ;
    Puttota, Silarin
    A new electrochemical sensor made from nanocomposite of manganese dioxide (MnO<inf>2</inf>)-antimony trioxide (Sb<inf>2</inf>O<inf>3</inf>) was fabricated on polyaniline (PANI) - patterned fluorine doped tin oxide (FTO) electrode (PANI/MnO<inf>2</inf>-Sb<inf>2</inf>O<inf>3</inf> nanocomposite/FTO) through a simple potentiostatic deposition method. The properties of the nanocomposite were characterized by field emission scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy and other electrochemical techniques. Such nanostructure combines the advantages of PANI (high conductivity and stability) with that of electrocatalytic species (good electrochemical activity). The sensor was applied for simultaneous determination of ascorbic acid (AA) and acetylsalicylic acid (ASA). The linear relationships between their current intensity and concentration were in the range of 6–265.42 nmol L<sup>− 1</sup> and 1.2–228.68 nmol L<sup>− 1</sup> with detection limit (S/N = 3) of 1.05 nmol L<sup>− 1</sup> and 0.20 nmol L<sup>− 1</sup>, respectively. Experimental results demonstrated that the sensor possesses high selectivity and suffers no interference from competing species. Moreover, it successfully detected AA and ASA in human urine samples with highly satisfactory results.