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Author: search.filters.author.Choengchan, NathawutSubject: search.filters.subject.Anti-aggregation

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    Direct determination of ethanol in alcoholic beverages based on its anti-aggregation of melamine-silver nanoparticle assembly
    (2022-12-01)
    Duangdeewong, Chomphunud
    ;
    Choengchan, Nathawut
    ;
    Wattanasin, Panwadee
    ;
    Teerasong, Saowapak
    We report a new method for determination of ethanol based on anti-aggregation of silver nanoparticles (AgNPs) in the presence of melamine. In the system, ethanol and melamine act as protecting and aggregating agents, respectively. Melamine can induce citrate-stabilized AgNPs to aggregate, leading to a color change from yellow to green. However, if the AgNPs are pre-incubated in ethanol, ethanol readily surrounds the particles by forming hydrogen bonds with the citrate stabilizer. An external nanoshell of ethanol hinders particle aggregation caused by melamine. Minor aggregation of AgNPs was observed, the solution color maintained its yellow-orange color. Higher ethanol concentrations result in a lower degree of particle aggregation. The colorimetric response of AgNPs was monitored using a UV–vis spectrophotometer at 390 nm. The current method could determine ethanol concentrations over a wide dynamic range of 5–80% (v/v), with a detection limit of 3.1% (v/v) (3SD of blank/slope). This method was applied for direct quantification of ethanol in alcoholic drinks without sample pretreatment and the results are well correlated with those of gas chromatography. Our method is convenient and cost effective, making it auspicious for ethanol monitoring in alcoholic drink manufacture and control.
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    A simple and rapid method based on anti-aggregation of silver nanoparticles for detection of poly(diallyldimethylammonium chloride) in tap water
    (2016-01-01)
    Trisaranakul, Wichaya
    ;
    Chompoosor, Apiwat
    ;
    Maneeprakorn, Weerakanya
    ;
    Nacapricha, Duangjai
    ;
    Choengchan, Nathawut
    A simple and rapid method was developed for the detection of poly(diallyldimethylammonium chloride) (PDADMAC) using citrate-capped silver nanoparticles (AgNPs). Detection was based on anti-aggregation of AgNPs in phosphate buffer caused by PDADMAC. Due to its positive charges, PDADMAC was adsorbed onto AgNPs via electrostatic interaction with citrate, which resulted in the charges at the particle surfaces to become positive and caused repulsion among particles. Furthermore, long-chain PDADMAC provided steric hindrance. These two effects promoted the dispersion of AgNPs in the phosphate buffer. A change in the state of dispersion influenced the surface plasmon resonance (SPR) of AgNPs. Therefore, in this work, the concentration of PDADMAC was determined by monitoring changes in absorbance (at 396 nm) caused by SPR of AgNPs. Under optimal conditions, the calibration was linear over the range of 1 to 100 mg L<sup>-1</sup> with a detection limit of 0.7 mg L<sup>-1</sup>. Satisfactory precision was obtained (RSD = 2.8%). This method was successfully applied to the determination of PDADMAC in tap water samples. The recoveries ranged from 86.0 - 107.5%.