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A scanner-based microplate platform for high-throughput oxytetracycline detection using diazotization-coupling chemistry with greenness evaluation
(2026-06-01)
Puttasa, Papawarin
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Ngernpimai, Sawinee
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Tippayawat, Patcharaporn
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Park, Myoung‑Hwan
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Teerasong, Saowapak
Routine oxytetracycline (OTC) monitoring of aquaculture effluents, water sources, and pharmaceutical products is essential for environmental management and regulatory compliance. However, existing analytical methods remain largely instrumental and low-throughput. Herein, a microvolume, high-throughput, scanner-based colorimetric microplate platform is developed for OTC determination using a sensitive and selective diazotization-coupling chemistry with RGB digital image analysis. Sulfanilamide is diazotized with nitrite to generate reactive diazonium species, which subsequently couple with OTC to form a strongly colored yellow-orange azo dye. Only microliter-scale volumes of reagents and samples are required in each well, and the reaction is completed within a few minutes, enabling simultaneous analysis of up to 96 samples. The microplate is imaged with a flatbed scanner, and color responses are quantified using ImageJ software. A linear calibration range of 1 − 40 μM was obtained with a detection limit of 0.33 μM. The platform was successfully applied to OTC determination in aquaculture effluents, tap water, drinking water, and pharmaceutical samples. It exhibited high selectivity against other antibiotics with no observable cross-reactivity. The green analytical procedure index (GAPI) confirmed the method’s environmental friendliness. Overall, the scanner-based microplate platform offers a simple, low-cost, portable, and high-throughput alternative to conventional OTC assays.
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Insights from dual-platform metabolomics on durian flowers: An alternative source of procyanidins from agricultural waste with bioactivities
(2025-07-01)
Potijun, Supakorn
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Pattarapipatkul, Nattaya
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Boonma, Pitchakorn
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Pewlong, Putthamas
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Pathtubtim, Intira
Procyanidins, which are polyphenol compounds in grape seeds, apples, and berries, are known for their anti-inflammatory and antioxidant properties. In this study, we investigated durian flowers, an agricultural waste, as a novel procyanidin source. Durian trees bloom prolifically, but not all flowers develop into mature fruits, representing underutilized resources. Dual-platform metabolomic analysis using ultra-high-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry and gas chromatography–mass spectrometry annotates polyphenols such as (−)-epicatechin, procyanidins B1, B2, and C1. The 80 % (v/v) ethanol extraction yielded a crude extract with a total procyanidin content of 7.68 mg/g. Bioactivity assays revealed that the procyanidin-rich crude extract reduced oxidative stress and exhibited anti-inflammatory effects against UVA in human keratinocytes (HaCaT). This study is the first to propose durian flowers as a sustainable and cost-effective procyanidin source with potential application in the nutraceutical and cosmeceutical industries, contributing significantly to the repurposing of agricultural waste through green technology.
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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
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Wangdi, Nidup
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Sonsa-ard, Thitaporn
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Teerasong, Saowapak
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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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Poly(vinyl alcohol) capped silver nanoparticles for antioxidant assay based on seed-mediated nanoparticle growth
(2017-08-01)
Teerasong, Saowapak
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Jinnarak, Amornrassamee
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Chaneam, Sumonmarn
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Wilairat, Prapin
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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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Nanoencapsulation of n-octadecane phase change material in self-assembled polyelectrolyte by soft solution technique
(2014-01-01)
Iamphaojeen, Yuwanda
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Siriphannon, Punnama
Nanoencapsulation of n-octadecane phase change material was performed by facile soft solution technique. An emulsion of n-octadecane and sodium dodecyl sulfate was prepared by high intensity sonication and then mixed with 1-6 mM of poly(diallyldimethylammonium chloride) (PDDA) solution. The capsules with globular core-shell structure were obtained via self-assembly of PDDA molecules coated on the primary emulsion droplets, described as PDDA encapsulated n-octadecane (PDDA-en-Oc). Average particle size and ζ-potential of PDDA-en-Oc increased with increasing of PDDA concentration due to the different PDDA conformation and thickness of capsules' shell. The smaller diameter of PDDA-en-Oc, the faster heat releasing and absorption were obtained. However, the increasing of PDDA concentration could improve the encapsulation efficiency, resulting in an increment of latent heat quantity. The PDDA-en-Oc capsules prepared from 4 mM PDDA with ∼166 nm in size possessed the maximum latent heat and encapsulation efficiency (i.e., 124.4 J/g and 58%, respectively). © 2014 Copyright Taylor & Francis Group, LLC.

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