Praditweangkum, Wiboon

Preferred name

Main Affiliation

School of Science

wiboon.pra@kmitl.ac.th

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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.
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A double-layered paper-based analytical device for speciation and simultaneous determination of iron in waters within single-shot analysis
(2025-08-01)
Thongchan, Surachet
;
Sookpotarom, Punyapat
;
Praditweangkum, Wiboon
;
Thongyoo, Panumart
;
Sojic, Neso
This work demonstrates the use of a paper-based analytical device (PAD) for the speciation and the simultaneous determination of iron (Fe) in waters within a single-shot analysis. The PAD is designed as having stacked, double layers viz., the topside and underside layers. Each layer (25 × 25 mm2) consists of a defined circular hydrophilic reservoir (10 mm Ø), situated in the adhesive glue-fabricated hydrophobic zone. Both layers are assembled by a two-sided mounting tape (3.0 mm thickness). The sample is introduced onto the topside reservoir and only Fe (II) reacts specifically with bathophenanthroline (Bphen) to form the stable, red-colored product. Consecutively, the sample flows vertically and exposes the underside reservoir. Then, the PAD is flipped, and the new class of the fluorescein derivative is transferred to the underside reservoir. Fe (III) selectively forms the complex with the fluorophore, and this results in quenching of the green, fluorescent light under UV irradiation. The optical image of each reservoir is captured via a smart phone camera under a light control studio and their color intensities are evaluated by ImageJ™ software. Under the optimal conditions, the calibrations, ranging from 0–0.5 mg L-1 Fe (II) and 0–10 mg L-1 Fe (III) are observed with good linearity (r2 > 0.99). Detection limits (3SD) of 0.02 mg Fe (II) L-1 and 0.21 mg Fe (III) L-1 are achieved. The developed PAD offers good recoveries (94.8–107 %) and high precision (RSD < 4 %). It is also successfully validated against the UV–visible spectrophotometric and the ICP-OES methods. The Fe contents are not significant differences at 95 % confidence under the statistical paired t-test (Fe(II): t<inf>cal</inf> = -0.28, t<inf>cri</inf> = 2.45 and Fe (III): t<inf>cal</inf> = 1.77, t<inf>cri</inf> = 2.45). Remarkedly, The PAD enables the simultaneous determination of Fe(II) and Fe(III) without cross- reactivity effect.
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A Microfluidic Paper-based Analytical Device for Simultaneous Measurement of Albumin, Creatinine and Uric Acid in Urine based on Standard Addition Method
(2024-01-03)
Wisaichon, Wannakan
;
Choengchan, Nathawut
;
Praditweangkum, Wiboon
This work describes a simple method for the simultaneous measurement of urinary albumin, creatinine and uric acid using a standard addition approach on a microfluidic paper-based analytical device (µPAD). Hydrophobic barrier of the µPAD was created by stamping indelible ink onto a filter paper. The µPAD was designed with a flower-liked configuration. After aliquoting urine to a central sample zone, the sample flowed to ten surrounding channels, namely “the inner channels”, where the blank (water) or standard solutions had been added. The inner channels were connected to circular reagent zones where reagents had been immobilized. Tetrabromophenolphthalein ethyl ester, alkaline picrate, and a mixed solution of ferric chloride and ferric cyanide were used as the chromogenic reagents for the colorimetric detections of albumin, creatinine, and uric acid, respectively. Each reagent zone was linked with a circular detection zone through a second channel, namely “the outer channels”. The blue-, orange-and greenish-blue colored products were observed in the detection zones for the measurement of albumin, creatinine, and uric acid, correspondingly. A digital image of the µPAD was captured with a mobile phone. The color intensities were evaluated by ImageJ™ and were employed for the quantitative analyses. The standard addition calibrations were found to be linear (r2 > 0.99) for the spiked analyte concentrations up to 100 mg L-1 albumin, 1000 mg L-1 creatinine, and 50 mg dL-1 uric acid. The paper platform provided high precision (RSD < 5 %) and good analytical recovery (91.8-109.7 %). Under paired t-test, the results obtained by the developed µPAD and the validating methods were not significantly different at 95 % confidence (albumin: t<inf>stat</inf> =-0.130, t<inf>cri</inf> = 3.182, creatinine: t<inf>stat</inf> =-0.133, t<inf>cri</inf> = 3.182, and uric acid: t<inf>stat</inf> = 1.119, t<inf>cri</inf> = 3.182).

Praditweangkum, Wiboon

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