Teerasong, Saowapak

Preferred name

Teerasong, Saowapak

Alternative Name

Teerasong, S.

Main Affiliation

School of Science

saowapak.te@kmitl.ac.th

Now showing 1 - 10 of 11

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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+ by gallic acid by providing nucleation seeds. Ag+ 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.
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A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection
(2010-05-15)
Sereenonchai, Kamonthip
;
Teerasong, Saowapak
;
Chan-Eam, Sumonmarn
;
Saetear, Phoonthawee
;
Choengchan, Nathawut
This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO<inf>2</inf> gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO<inf>2</inf> gas into the acceptor stream changes the conductivity of the acceptor solution causing an increase of signal at the capacitively coupled contactless conductivity detection (C4D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on 'membraneless vaporization' (MBL-VP). The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33-99% (w/w) CaCO<inf>3</inf>). Analysis of samples by this method is direct and convenient as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision. © 2010 Elsevier B.V.
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Colorimetric sensor using silver nanoparticles for determination of hydrogen peroxide based on a flow injection system
(2013-09-01)
Teerasong, Saowapak
;
Sonsa-Ard, Thitaporn
;
Vimolkanjana, Chavin
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Choengchan, Nathawut
;
Chompoosor, Apiwat
In this work, a colorimetric probe using a flow injection (FI) system and silver nanoparticles (AgNPs) was developed for determination of hydrogen peroxide (H2O2) concentration. AgNPs have catalytic ability for decomposition of H2O2, producing silver ions and superoxide. The reaction mechanism of H2O2 and AgNPs at various concentrations is described. H2O2 concentration was quantified by monitoring decrease in AgNPs surface plasmon resonance during the decomposition reaction. Under the optimum condition, the detection limit for H2O2 was 0.6 mg/l. The flow system developed in this study provided good precision of analysis (relative standard deviation = 2.97%) with high throughput (18 samples/h). This method was successfully applied to analysis of H2O2 in pharmaceutical and household products. Therefore, the method is feasible for on-line monitoring H2O2 in manufacturing process quality control. © Copyright 2013 American Scientific Publishers All rights reserved.
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Microfluidic paper-based analytical device for convenient use in measurement of iodate in table salt and irrigation water
(2020-01-01)
Duangdeewong, Chomphunud
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Sitanurak, Jirayu
;
Wilairat, Prapin
;
Nacapricha, Duangjai
;
Teerasong, Saowapak
We report a convenient microfluidic paper-based analytical device (µPAD) for the determination of iodate. The µPAD was fabricated using an ink-stamp with a simple circle design. Colorimetric detection of iodate employs the oxidation of hydroxylamine by the iodate to generate nitrite which reacts with the Griess reagent producing an intense magenta color. The images were recorded by a digital camera, and converted to a green scale color intensity by ImageJ. Calibration of iodate was linear in the range of 50–400 mg L−1 with a detection limit of 38.1 mg L−1. With such a wide linear range, the method can be applied to various kinds of samples with the entire process completed in 50 s. Good precision of measurement was obtained (<2 %RSD). Iodate levels were determined using the µPADs in table salt and irrigation water samples. The measured concentrations of the samples correlated well with the values as found by the standard iodometric titration (no statistical difference at a 95% confidence level). The developed device is simple with easy fabrication and rapid operation. It is portable and cost-effective and therefore suitable for quality control of iodate levels in the manufacturing and agricultural industries.
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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−1 GABA, with a lower limit of detection of 39.6 mg L‐1. 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).
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A simple method based on one phase measurement for determination of the octanol-water partition coefficient of drugs
(2015-01-01)
Teerasong, Saowapak
;
Wattanasin, Panwadee
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Wilairat, Prapin
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Nacapricha, Duangjai
The octanol-water partition coefficient (P<inf>ow</inf>) is widely used to assessment of lipophilicity of drug. The Pow can be measured by determining the ratio of the concentration of the drug in octanol to its concentration in water at equilibrium. In the standard method, two calibration curves are required in order to obtain the concentration of drug in the two phases. The procedure is thus tedious and time consuming. In this work, a simple approach for determining the P<inf>ow</inf> of drug is described. Only the absorbance of one phase and volumes of octanol and water are used in the calculation; calibration curves are no longer required, making the procedure much more convenient. The method was applied to examples of hydrophobic and hydrophilic drugs. The P<inf>ow</inf> values obtained by our method agreed well with literature values (R2 = 0.998). This method is simple and capable for screening new drugs in a stage of drug discovery.
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Zone fluidics for measurement of octanol-water partition coefficient of drugs
(2015-02-20)
Wattanasin, Panwadee
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Saetear, Phoonthawee
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Wilairat, Prapin
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Nacapricha, Duangjai
;
Teerasong, Saowapak
A novel zone fluidics (ZF) system for the determination of the octanol-water partition coefficient (P<inf>ow</inf>) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the P<inf>ow</inf>. The developed system was applied to the determination of the P<inf>ow</inf> of some common drugs. The log (P<inf>ow</inf>) values agreed well with a batch method (R2=0.999) and literature (R2=0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of P<inf>ow</inf> values in the drug discovery process.
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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
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Chompoosor, Apiwat
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Maneeprakorn, Weerakanya
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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-1 with a detection limit of 0.7 mg L-1. 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%.
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Simple and green method for direct quantification of hypochlorite in household bleach with membraneless gas-separation microfluidic paper-based analytical device
(2018-09-01)
Sitanurak, Jirayu
;
Wangdi, Nidup
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Sonsa-ard, Thitaporn
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Teerasong, Saowapak
;
Amornsakchai, Taweechai
This work presents development of a microfluidic paper-based analytical device (µPAD) for direct determination of hypochlorite in household bleach. The recent design of a membraneless gas-separation microfluidic paper-based analytical device (MBL-GS µPAD) was employed to fabricate the hypochlorite-µPAD. Chlorine gas is generated in the µPAD via acidification of an aliquot of sample loaded on to the donor reservoir located at the bottom layer of the μPAD. The liberated chlorine gas diffuses through the air space to oxidize iodide ion previously impregnated in the acceptor reservoir at the top layer of the μPAD, leading to formation of the brown color of the tri-iodide ions. Digital image of the brown zone was captured at exactly 5 min after loading the acid. Image J program is used for analysis of the image for quantification of the hypochlorite in unit of g Cl<inf>2</inf> L−1. It was found that employing a relatively large volume of the air space (ca. 270 µL) direct analysis of the high concentration of hypochlorite in the bleach was achieved without prior dilution. The method thus provides a linear working range of 25–100 g Cl<inf>2</inf> L−1, which is suitable for most commercial household products. The calibration line has a coefficient of determination of 0.999. The precision of measurements is 0.96% RSD and 0.30% RSD at 30 g Cl<inf>2</inf> L−1 and 80 g Cl<inf>2</inf> L−1 (n = 10), respectively. Using the paired t-test (P = 0.05, n = 8), the method agreed well with the iodometric titration method. Our μPAD for hypochlorite is portable and cost-effective. The method is also “green” since there is a significant reduction in use of reagents compared to other conventional methods.
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A Screen Printed Graphene Based Electrochemical Sensor for Single Drop Analysis of Hydroquinone in Cosmetic Products
(2019-08-01)
Duekhuntod, Wannida
;
Karuwan, Chanpen
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Tuantranont, Adisorn
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Nacapricha, Duangjai
;
Teerasong, Saowapak
A graphene modified carbon paste sensor (or so-called graphene based sensor) was developed for electrochemical detection of hydroquinone. The sensor was fast fabricated using screen-printing technique. By integrating three fundamental electrodes on a single device, the sensor is small and portable. A determination is based on a one drop analysis. A 60 μ.L-drop of sample was placed onto the sensor prior to cyclic voltammetric measurement. The method relies on green analysis since it lowers the consumption of sample and waste generation. Under the optimal conditions, a linear calibration was achieved in range of 1.0 x 10-4 to 5.0 x 10-3 M hydroquinone. The detection limit was 7 x 10-5 M, a sensitive adequate for measuring hydroquinone in cosmetic products. The sensor provided good precision (%RSD = 2.78) and accuracy (recoveries = 87-114%), with analysis times of less than a minute. The sensor was applied to determine the presence of hydroquinone in whitening creams. The results obtained from the developed sensor satisfactorily agreed with the HPLC method, indicating the reliability of the method. Due to its advantages in terms of rapidity, low-cost and portability, the device is a viable choice for on-site screening for hydroquinone contamination in whitening products.

Teerasong, Saowapak

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