Teerasong, Saowapak

Preferred name

Teerasong, Saowapak

Alternative Name

Teerasong, S.

Main Affiliation

School of Science

saowapak.te@kmitl.ac.th

Now showing 1 - 6 of 6

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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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Supramolecular electrochemical detection of bisphenol A using a melamine-functionalized reduced graphene oxide modified screen-printed electrode
(2026-06-01)
Thammaso, Supinya
;
Kamsong, Wichayaporn
;
Karuwan, Chanpen
;
Saetear, Phoonthawee
;
Detsri, Ekarat
Detection of bisphenol A (BPA), an endocrine disruptor, requires rapid and reliable methods to ensure water safety. In the current work, we present a supramolecular electrochemical sensor based on a melamine-immobilized reduced graphene oxide-modified screen-printed carbon electrode (Mel-rGO SPE) for the determination of BPA. The sensing design exploits dual supramolecular interactions: hydrogen bonding between melamine's amine groups and BPA's hydroxyl moieties, and π–π stacking between their aromatic rings. While rGO significantly enhances electron transfer, these synergistic effects improve device sensitivity. A Mel-rGO SPE was fabricated using an ink-mixing approach to produce a uniform and robust sensor. BPA detection was performed using cyclic voltammetry, and the anodic peak potential was 0.32 V. The current response provided a good correlation with BPA concentrations in the range of 1–250 μM. The detection limit was low, 0.23 μM. The Mel-rGO SPE was successfully applied to determine BPA in polycarbonate bottled water. These promising results indicate that the developed sensor is an alternative device for rapid screening of BPA contamination of water samples.
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Hydrophobic barrier-free laminated paper-based analytical device (LPAD) using a diameter-based measurement for determination of iodide in pharmaceutical products
(2024-08-01)
Noirahaeng, Nakarin
;
Salungyu, Jirawat
;
Teerasong, Saowapak
;
Uraisin, Kanchana
;
Saetear, Phoonthawee
This work presents, for the first time, an exploitation of an argentometric Mohr's method for iodide detection using diameter-based measurement on laminated paper-based analytical device (LPAD). Our LPAD is simplified fabricated with no required hydrophobic barrier for patterning a detection flow channel. In the absence of a flow channel, the liquid is imbibed radially into the filter paper outward from the small center inlet hole. This imbibition leads to the measurement of diameter after the formation of the precipitation product. For LPAD, a rectangular piece of Whatman filter paper is cut and positioned between a top laminating sheet, which has a hole punched for inlet, and a bottom laminating sheet. The central inlet hole enables access to the liquid on the paper. For iodide analysis, silver nitrate is dispensed first, followed by the iodide standard/sample. This process leads to the formation of pale-yellow silver iodide solids on the paper. The chromate indicator solution is subsequently loaded to the paper. The color of the chromate solution imparts a tint to the circular band of silver iodide solids, resulting in an intense yellow color. When the silver iodide precipitates are stained, the chromate solution typically serves as an indicator, chemically reacting to an excess silver nitrate solution moistened on paper. This reaction generates an outer reddish-brown ring of silver chromate. The distinct color contrast between the intense yellow (tinted silver iodide) and reddish-brown (silver chromate) allows for clear observation of the measurement boundary, facilitating diameter-based measurements of the circular band of silver iodide. We demonstrate the applicability in analysis of pharmaceutical KI tablets. The quantitative results obtained from diameter-based measurement LPAD show good agreement with those obtained from the potentiometric method. Our hydrophobic barrier-free LPAD is rapid, cost-effective, low liquid consumption and applicable for onsite analysis.
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Zone fluidics for measurement of octanol-water partition coefficient of drugs
(2015-02-20)
Wattanasin, Panwadee
;
Saetear, Phoonthawee
;
Wilairat, Prapin
;
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 rapid cotton swab for on-site screening of coloring curcumin on durian skin: food safety aspects
(2023-08-01)
Teerasong, Saowapak
;
Boonyaratsewee, Phanaporn
;
Aunruan, Panuwat
;
Saard, Worawan
;
Saetear, Phoonthawee
Exported durians from Thailand are sometimes immersed in curcumin to give the fruits a good appearance. Curcumin is regarded as non-toxic additive, however some importing countries prohibited use of any additive to fresh fruits and vegetables. This work aims to develop a rapid, low cost and convenient cotton swab device for curcumin detection. The detection principle involves a colorimetric acid–base characteristic of curcumin. Curcumin in an acidic/neutral solution presents a bright yellow color, while it displays an intense orange–red color in basic solution. A cotton swab acted for both sample collection and as a sensing platform. A pre-moistened swab was used to wipe a durian surface. Afterward, a NaOH solution was dropped onto the swab. A distinct orange–red color appearing on the swab indicates the presence of curcumin. The cotton swab was applied for qualitative analysis of curcumin contaminated on durian husks via visual detection. The developed device provided good reliability, 93.75% (36 samples). Furthermore, the device was demonstrated for quantitative determination using camera detection. Two linear calibrations were obtained in ranges of 10–75 and 75–250 mg L−1, with a detection limit of 3.2 mg L−1. The method was also successfully applied to quantification of curcumin in durians (three samples) and dietary supplements (two samples). The test can be done in a few minutes. The developed device was established as an useful tool for food safety and control of contamination by curcumin in an on-site application. Graphical abstract: [Figure not available: see fulltext.]
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Reagent-free analytical flow methods for the soft drink industry: Efforts for environmentally friendly chemical analysis
(2012-10-25)
Mantim, Thitirat
;
Saetear, Phoonthawee
;
Teerasong, Saowapak
;
Chan-Eam, Sumonmarn
;
Sereenonchai, Kamonthip
The evolution of an entirely green analytical system for industrial quality control of carbonated drinks is described. The developed flow system is capable of providing analytical data of the dissolved CO <inf>2</inf>, sucrose, and color of a sample consecutively in real-time. The system has been carefully designed on the basis of "reagent-free", meaning that no added chemicals are required for the analysis. The system first vaporizes CO <inf>2</inf> from the soft drink in a gas-liquid separation chamber, with a channel for a flow of pure water as the CO <inf>2</inf> acceptor. The dissolved CO <inf>2</inf> alters the conductivity of the water stream, which is directly related to the concentration of CO <inf>2</inf> in the soft drink. The sucrose content is measured based on the "schlieren effect", the sample plug flows out of the vaporization chamber into a colorimeter with a near-infrared/light-emitting diode (NIR/LED) as light source. The schlieren effect arises at the boundary of pure water and soft drink with refraction of light in proportion to the sugar concentration. The system also measures the absorbance of the sample using an RGB-LED. The related principles and preliminary experiments as proof of concept are described as well as the construction of the flow system for this completely reagent-free analyzer. A simple flow injection system using the schlieren effect was also developed for rapid quantitative analysis of sugar in noncarbonated soft drinks. © 2012 IUPAC.

Teerasong, Saowapak

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