Choengchan, Nathawut

Preferred name

Alternative Name

Choengchan, N.

Choengchan, Nuthawut

Main Affiliation

School of Science

nathawut.ch@kmitl.ac.th

Now showing 1 - 10 of 29

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A "dual-acceptor channel" membraneless gas-diffusion unit for simultaneous determination of ethanol and acetaldehyde in liquors using reverse flow injection
(2018-01-01)
Choengchan, Nathawut
;
Poontong, Bangerdsuk
;
Mathaweesansurn, Arjnarong
;
Maneerat, Noppadol
;
Motomizu, Shoji
A new design of membraneless gas-diffusion unit with dual acceptor channels for separation, collection and simultaneous determination of two volatile analytes in liquid sample is presented. The unit is comprised of three parallel channels in a closed module. A sample is aspirated into the central channel and two kinds of reagents are introduced into the other two channels. Two analytes are isolated from the sample matrix by diffusion into head-space and absorbed into the specific reagents. Non-absorbed vapor is released by opening the programmable controlled lid. The unit was applied to liquors for measurement of ethanol and acetaldehyde using reverse flow injection. Dichromate and nitroprusside were exploited as reagents for colorimetric detection of ethanol and acetaldehyde, respectively. Good linearity ranges (r2 > 0.99) with high precision (RSD < 2%) and high accuracy (recovery: 90 - 105%) were achieved. The results were compared to the results by GC-FID and no significant difference was observed by paired t-test (95% confidence).
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A new coumarin-based “OFF–ON” fluorescent sensor for H2S detection in HeLa cells
(2025-02-05)
Sontisiri, Pakornsiri
;
Promrug, Dusit
;
Arthan, Dumrongkiet
;
Choengchan, Nathawut
;
Thongyoo, Panumart
A new “OFF–ON” coumarin-based fluorescent probe for H<inf>2</inf>S detection was designed and successfully developed through O-sulfonylation between a dabsyl quencher and 7-hydroxy-4-methylcoumarin as a fluorescent reporter, based on a FRET approach. This H<inf>2</inf>S responsive probe, utilizing H<inf>2</inf>S assisted thiolysis of a sulfonate ester as the sensing strategy, demonstrated excellent performance towards H<inf>2</inf>S with a limit of detection (LoD) of 1.64 µM, along with superb selectivity, good stability and high specificity towards H<inf>2</inf>S without interference from other biomarkers and analytes. Moreover, dabsyl-7-hydroxy-4-methylcoumarin (dabsylcoumarin) is capable of permeating the cell membrane and effectively visualizing the level of H<inf>2</inf>S in the living HeLa cells without cytotoxicity.
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Low-cost synthesis of gold nanoparticles from reused traditional gold leaf and its application for sensitive and selective colorimetric sensing of creatinine in urine
(2020-01-01)
Mathaweesansurn, Arjnarong
;
Choengchan, Nathawut
;
Khongkaew, Putthiporn
;
Phechkrajang, Chutima M.
Background: Gold nanoparticles (Au NPs) are normally prepared using standard gold (III) trichloride which is much expensive and irritant. This work is aimed at demonstrating simple and low-cost synthesis of Au NPs from the reused traditional gold leaf which is cost-free and less toxic. Methods: The reused gold leaf was donated by the local temple. It was digested and used as the precursor for the preparation of the Au NPs by Turkevich method. Poly (vinyl alcohol) (PVA) was em-ployed as a stabilizer. The as-prepared Au NPs were applied for the colorimetric determination of creatinine in urine without any sample pretreatment. Results: Long-term stability of the gold colloids was achieved for at least 3 months. Morphology and purity of the as-prepared Au NPs were the same as the ones prepared from standard gold (III) salt and standard gold foil. Colorimetric response of the Au NPs was linear to the standard creatinine up to 200 mg L-1. The limit of detection (0.16 mg L-1 or 1.41 µM) was enough sensitive for urinary cre-atinine detection in patients with kidney disease. Good recoveries (97-108%) and fast analysis time (3 min) were achieved. The developed method was successfully validated against the HPLC method. Conclusion: Facile and cost-effective synthesis of the Au NPs from the reused traditional gold leaf, was accomplished. The as-prepared Au NPs were successfully applied for the determination of urinary creatinine with high sensitivity and selectivity.
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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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A Double-layered Paper-based Analytical Device for Determination of Iron in Water Samples based on Standard Addition Method
(2024-01-03)
Srikritsadawong, Pongpichet
;
Sookpotarom, Punyapat
;
Thongchan, Surachet
;
Choengchan, Nathawut
A simple method for the determination of iron involved a novel paper-based analytical device (PAD) was developed. The PAD was composed of two layers. Each layer contained a circular hydrophilic reservoir (10 mm Ø) that was situated in a rectangular filter paper (25 Î 25 mm2). The hydrophobic area was created by painting the paper with a “waterproof” glue. The top and the bottom layers were assigned as “the filtration” and “the detection” platforms, respectively. The procedure was started by pipetting an aliquot of bathophenanthroline (Bphen) onto the hydrophilic zone of the bottom layer followed by spiking of standard solutions (0.1-0.5 mgL-1 Fe2+). The red complex was developed. Then, the top and the bottom layers were assembled by two-sided mounting tape. Later, a water sample was dropped onto the top layer, which removed (filtered) any suspended particles in the water sample. When the filtrate was exposed to the bottom layer, a further colored product formed. The bottom layer was removed and placed in a light-controlled box, and the optical image of the product was captured using a smartphone. Its intensity was evaluated through ImageJ™. Linear standard addition plots were obtained (r2 > 0.99). The PAD provided high precision (RSD < 6%) with good recovery (92.6-102%). It was applied to the analysis of drinking, tap, canal and river water samples without any prior filtration. The iron amounts were compared to the results obtained by the spectrophotometric method, and there was not significantly difference at 95% confidence (Paired-t test, n = 5 samples, t<inf>stat</inf> = 2.68, t<inf>cri</inf> = 2.78).
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A mobile phone-based analyzer for quantitative determination of urinary albumin using self-calibration approach
(2017-04-01)
Mathaweesansurn, Arjnarong
;
Maneerat, Noppadol
;
Choengchan, Nathawut
This work demonstrates use of a smart mobile phone installed with an Android application, termed ‘Albumin smart test’, as an analyzer for quantitative determination of urinary albumin. The reaction between albumin and tetrabromophenolphthalein ethyl ester (TBPE) in the presence of Triton X-100 was employed for detection principle.The mobile phone was exploited with the sample cassette and the test paper. One sample cassette composes of two holders for accommodation of control and test samples. The test paper was designed in order to contain standard colorimetric strip and space for situating the sample cassette. Optical images of the strip and the samples were simultaneously captured in a single shot by a digital camera of the mobile phone and were digitally processed by the developed application for quantification of the albumin concentration based on self-calibration approach. With the advantage of self-calibration, the albumin test by our mobile phone can be performed in ambient light without using any extra module integrated with lighting control device. The other advantages are portability, ease of implementation and rapid analysis (3 min) with high precision (RSD ≤ 2.5%) and high accuracy (Recovery = 98.7% ± 1.6). The mobile device was successfully applied to diagnosis of microalbuminuria.
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Towards direct analysis of solid and liquid samples exploiting a 3D printed dialysis unit and sequential injection: Application for automated derivatization and determination of gamma-aminobutyric acid in foodstuff and beverages
(2020-02-08)
Kasetsoontorn, Bhoonnarasa
;
Choengchan, Nathawut
In this work, a new design of a dialysis unit for direct analysis of solid and liquid samples is presented. The homemade unit was constructed using a 3D printer due to its simple and fast fabrication ability. The dialysis unit is composed of cylindrical-shaped donor and acceptor chambers. A stainless steel sieve is installed inside the donor chamber. SEM images clearly showed that the sieve prevented membrane blockage by suspension particles in the sample. Multiple dialysis units were connected to a sequential injection (SI) system for serial determination of gamma-aminobutyric acid (GABA) in solid and liquid samples. The dialysate from each dialysis unit was consecutively aspirated into the SI flow line for on-line derivatization of GABA with 2-hydroxy-1-naphthaldehyde (3.0% w/v). The derivative was detected spectrophotometrically at 425 nm. The linear calibration range extended to 1000 mg L−1 GABA (r2 > 0.99) with high precision (1.2 %RSD). The developed system was applied to analysis of dietary supplements, grains of germinated brown rice and milk. The samples were directly introduced into the donor chamber either as powder or liquids. The measured GABA content using the developed method was compared using high performance liquid chromatography, with good agreement using Pearson's correlation (r2 = 0.9999). The method has high accuracy based on recovery studies (99.8 ± 1.5%) and high sample throughput (64 samples h−1).
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Microfluidic analysis with front-face fluorometric detection for the determination of total inorganic iodine in drinking water
(2018-01-01)
Inpota, Prawpan
;
Strzelak, Kamil
;
Koncki, Robert
;
Sripumkhai, Wisaroot
;
Jeamsaksiri, Wutthinan
A microfluidic method with front-face fluorometric detection was developed for the determination of total inorganic iodine in drinking water. A polydimethylsiloxane (PDMS) microfluidic device was employed in conjunction with the Sandell-Kolthoff reaction, in which iodide catalyzed the redox reaction between Ce(IV) and As(III). Direct alignment of an optical fiber attached to a spectrofluorometer was used as a convenient detector for remote front-face fluorometric detection. Trace inorganic iodine (IO <inf>3</inf> - and I - ) present naturally in drinking water was measured by on-line conversion of iodate to iodide for determination of total inorganic iodine. On-line conversion efficiency of iodate to iodide using the microfluidic device was investigated. Excellent conversion efficiency of 93 - 103% (%RSD = 1.6 - 11%) was obtained. Inorganic iodine concentrations in drinking water samples were measured, and the results obtained were in good agreement with those obtained by an ICP-MS method. Spiked sample recoveries were in the range of 86%(±5) - 128%(±8) (n = 12). Interference of various anions and cations were investigated with tolerance limit concentrations ranging from 10-6 to 2.5 M depending on the type of ions. The developed method is simple and convenient, and it is a green method for iodine analysis, as it greatly reduces the amount of toxic reagent consumed with reagent volumes in the microfluidic scale.
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A highly selective 'turn-on' fluorescent sensor for Zn2+ based on fluorescein conjugates
(2016-03-09)
Chantalakana, Khwanchanok
;
Choengchan, Nathawut
;
Yingyuad, Peerada
;
Thongyoo, Panumart
A highly selective fluorescent chemosensor was designed, synthesized, and evaluated for Zn2+ recognition based on the photoinduced electron transfer (PET) mechanism. This azofluorescein was comprised of a fluorescein moiety acting as a fluorophore, a linker (-N=N-) and a novel ionophore receptor generated by the coordination of the linker (-N=N-) with phenoxyl and carboxyl functionalities to render a binding pocket for Zn2+ recognition. In the presence of Zn2+, a marked enhanced fluorescence change of 10-fold was observed. Under optimized conditions, a linear relationship between the fluorescence intensity and concentration of Zn2+ was observed with a detection limit of 1.2 μM. This probe also exhibited selectivity for Zn2+ over other metals ions, especially Cd2+. The binding constant of the Zn2+-azofluorescein complex was determined to be 2.4 × 104 M-1.
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Multi-well plate as headspaces for paper-based colorimetric detection of sulfur dioxide gas: An alternative method of sulfite titration for determination of formaldehyde
(2023-01-25)
Yodpach, Nattapon
;
Chantiwas, Rattikan
;
Wilairat, Prapin
;
Choengchan, Nathawut
;
Praditweangkum, Wiboon
This work describes the analysis of formaldehyde using a 96-well microplate as multiple headspaces for the separation of sulfur dioxide gas generated from the sulfite remaining after its reaction with the formaldehyde in the sample. The quantitation of the gas is by colorimetric detection of an indicator paper placed over the microplate. The samples are aqueous extracts of various foods that are possibly adulterated with formaldehyde. A known excess amount of sulfite is added to the extract solution aliquoted in the well. The remaining sulfite is acidified with hydrochloric acid to generate sulfur dioxide gas which diffuses through the headspace above the solution to be absorbed at the moist strip of the indicator paper placed over the mouth of the wells. Anthocyanins extracted from the butterfly pea flower is used as the pH indicator giving a color change from the increase of hydrogen ions by hydrolysis of the absorbed sulfur dioxide gas. The exposed paper strip is scanned, and the digital images of the colored region analyzed using ImageJ software. The optimized method has a linear range of 200–1000 mg L−1 formaldehyde with limit of detection ((2.57*SD of intercept)/(slope of calibration line)) of the aqueous extract of 40 mg L−1 and coefficient of determination (r2) > 0.9979. Samples of fresh produce, such as seafood, meat, and vegetables, and various processed food were analyzed for their possible formaldehyde content. The results obtained from the headspace paper-based colorimetric detection are not statistically different from the values obtained from the titration method by paired t-tests.

Choengchan, Nathawut

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