Teerasong, Saowapak

Loading...
Thumbnail Image
Preferred name
Teerasong, Saowapak
Alternative Name
Teerasong, S.
Main Affiliation
Email
saowapak.te@kmitl.ac.th

Settings

Now showing 1 - 3 of 3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Poly(vinyl alcohol) capped silver nanoparticles for antioxidant assay based on seed-mediated nanoparticle growth
    (2017-08-01)
    Teerasong, Saowapak
    ;
    Jinnarak, Amornrassamee
    ;
    Chaneam, Sumonmarn
    ;
    Wilairat, Prapin
    ;
    Nacapricha, Duangjai
    A simple and rapid method for measurement of total antioxidant capacity (TAC) was developed. In this work, gallic acid was used as the antioxidant standard. Poly(vinyl alcohol) embedded silver nanoparticles (PVA-AgNPs) were employed as a colorimetric sensor. The detection principle was based on the seed-mediated nanoparticle growth technique. The PVA-AgNPs act as a catalyst in the reduction of Ag<sup>+</sup> by gallic acid by providing nucleation seeds. Ag<sup>+</sup> was reduced to Ag° and accumulated on the PVA-AgNP surface, leading to an increase in the size of particles. The absorbance of the colloidal solution was drastically enhanced with a small red shift. Under optimal conditions, a linear response was established between the change in absorbance and the TAC value expressed in terms of gallic acid equivalents. The linear range was from 25 to 200 μM with a detection limit of 22.1 μM. Satisfactory precision was obtained with % relative standard deviation (RSD) of 2.17. The developed sensor was successfully applied for TAC assessment of commercial ginger products. The PVA-AgNP sensor offers rapid analysis (within 5 min) compared to other nanoparticle-based antioxidant assays. Synthesis of the particles and assay involved less-toxic chemicals, and is therefore a “greener” method.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    A novel colorimetric method for detection of gamma-aminobutyric acid based on silver nanoparticles
    (2016-06-28)
    Jinnarak, Amornrassamee
    ;
    Teerasong, Saowapak
    A novel, simple and rapid colorimetric method for determination of gamma-aminobutyric acid (GABA) was developed using a negatively charged citrate-capped silver nanoparticle (AgNP) probe. At an acidic pH of 3.8, GABA had a positive charge due to a protonation of amine groups. Therefore GABA could induce an aggregation of AgNPs due to electrostatic interaction. This caused a decrease in the surface plasmon resonance spectra of the colloidal solution at wavelength of 390 nm with a slight red shift. At the same time, the color of the suspension turned from yellow to green upon aggregation. Quantification of GABA was done spectrophotometrically. Under optimum conditions, the method showed a linear calibration in range of 100-500 mg L<sup>-1</sup> GABA, with a detection limit of 57.7 mg L<sup>-1</sup>. The method was successfully applied to measure GABA quantities in dietary supplements.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Sequential injection for determination of gamma-aminobutyric acid based on its effect on second order light scattering of silver nanoparticles
    (2016-08-01)
    Jinnarak, Amornrassamee
    ;
    Anantavichian, Pattarapon
    ;
    Intanin, Apichai
    ;
    Fungladda, Suchada
    ;
    Choengchan, Nathawut
    An automated sequential injection (SI) with second order light scattering (SOS) detection for determination of gamma-aminobutyric acid (GABA) was developed. Quantitation is based on electrostatic interaction between GABA and citrate-capped silver nanoparticles (AgNPs). In acetate buffer at pH 3.8, the positively charged GABA induces the nanoparticles to aggregate. This results in a change of light scattering monitored using a spectrofluorometer. In this work, working standard solutions of GABA were prepared in-line by the SI system pumping appropriate volumes of a stock solution of GABA and acetate buffer into a holding coil. Solution of AgNPs was subsequently drawn into the coil. The reaction zone was then transferred to the spectrofluorometer, set with excitation and detection wavelengths at 300 and 600 nm, respectively. Under optimised condition, the SOS intensity was proportional to the concentration of GABA. As a result, a linear curve was obtained in the range of 100–400 mg L<sup>−1</sup> GABA, with a lower limit of detection of 39.6 mg L<sup>‐1</sup>. Good precision of analysis was achieved, with 0.6 and 3.3% relative standard deviation (RSD) for external calibration (n = 5) and standard addition (n = 3), respectively. The developed method was successfully applied for quantification of GABA in dietary supplements (2 samples) and samples of instant green tea (2 samples).