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Magnetic Fe3O4/BiOBr for solar-light-responsive photodegradation of tetracycline antibiotic
(2026-07-01)
Detrat, Natthakitta
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Matsombat, Kanokwan
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Nonthing, Sattra
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Panchakeaw, Atchawadee
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Dulyasucharit, Ruethaithip
Magnetic Fe<inf>3</inf>O<inf>4</inf>/BiOBr photocatalyst was synthesized via an ultrasonic route. It was then applied for detoxification of tetracycline (TC) antibiotic. The prepared BiOBr exhibited E<inf>g</inf> of 2.71 eV while the binary Fe<inf>3</inf>O<inf>4</inf>/BiOBr showed E<inf>g</inf> of 2.04 eV. The Fe<inf>3</inf>O<inf>4</inf>/BiOBr photocatalyst displayed lower photoluminescence signal than BiOBr, suggesting the improvement of the electron-hole separation rate after creation of the magnetic Fe<inf>3</inf>O<inf>4</inf>/BiOBr photocatalyst. The promising photocatalytic efficiency of 100% was obtained. The corresponding enhanced rate constant of 0.0732 min−1 was achieved. The synthesized Fe<inf>3</inf>O<inf>4</inf>/BiOBr exhibited the promising photocatalytic performance and the excellent structural stability after five cycles of use. The superoxide anion radicals are the main active species involved in the degradation of the pollutant. The present paper demonstrates a novel way to fabricate the sunlight-responsive photocatalyst, with magnetic separable property, for decontamination of TC drug in aqueous phase.
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Miniaturized chromate-free chloride assay in fish sauce based on linear height calibration of AgCl precipitate in inverted microtubes
(2026-06-01)
Chantiwas, Rattikan
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Wilairat, Prapin
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Putthasa, Papawarin
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Cheotchinda, Benjamapohn
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Teerasong, Saowapak
A miniaturized, chromate-free methodology for chloride determination in high-salt food matrices is presented in accordance with the principles of Green Analytical Chemistry. Classical argentometric precipitation is adapted to a microvolume, instrument-light assay by confining silver chloride formation within inverted microcentrifuge tubes and directly measuring the height of the compact precipitate layer using a simple ruler. Because the cylindrical tube region has a constant cross-sectional area, precipitate height is directly proportional to chloride concentration, enabling straightforward linear calibration without optical detection, signal transduction, or complex data processing. Controlled tube inversion and low-speed centrifugation ensure that precipitation occurs exclusively within this cylindrical zone, producing a sharp, reproducible solid–liquid interface. Under optimized conditions (150 µL sample volume and 180 µL of AgNO₃ in nitric acid; centrifugation at 600 rpm for 3 min followed by 5 min settling), the method provides a linear working range of 50–500 mM chloride (r² = 0.9988), a detection limit of 14 mM, and relative standard deviations of 3–4 % at 200–300 mM. Validation of 12 commercial Thai fish sauce samples showed no statistically significant differences compared to AOAC potentiometric titration at the 95% confidence level, with recoveries of 100–103 % and %RSD values of 1–4.2 %. The primary advantage of this method is its strictly linear height–concentration relationship, enabled by geometry-controlled confinement of the precipitate. Unlike other miniaturized or paper-based assays, it eliminates the need for image analysis or device fabrication. From a green chemistry perspective, the assay eliminates the use of potassium chromate indicators and disposable paper-based devices, operates at the microliter scale using reusable plastic microtubes, and requires only low-speed centrifugation. Analytical Greenness (AGREE), Analytical Eco-scale, Green Analytical Procedure Index (GAPI), and White Analytical Chemistry (WAC) evaluations (AGREE score: 0.76; Eco-scale: 83; WAC score: 88.9) classify the method as an excellent example of green analysis. The proposed approach offers a robust and sustainable screening tool for chloride determination in high-salt foods.
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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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Supramolecular electrochemical detection of bisphenol A using a melamine-functionalized reduced graphene oxide modified screen-printed electrode
(2026-06-01)
Thammaso, Supinya
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Kamsong, Wichayaporn
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Karuwan, Chanpen
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Saetear, Phoonthawee
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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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Smartphone-based disposable cotton-swab sensor loaded with creatinine/Cu–chlorophyllin–stabilized AuNPs for ultrasensitive RGB colorimetric detection of mercury (II) ions in aquatic environments
(2026-05-01)
Lerdpiriyaskulkij, Natee
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Detsri, Ekarat
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Teerasong, Saowapak
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Chansai, Sarayute
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Mathaweesansurn, Arjnarong
A simple, rapid, selective, and sensitive colorimetric sensor based on a disposable cotton swab loaded with Au nanoparticle–modified Cu-chlorophyllin (Au0–NPs<inf>CHL</inf>) and creatinine was developed for mercury (II) detection in aquatic environments using smartphone–based RGB analysis. Au0–NPs<inf>CHL</inf> were synthesized by ultrasonic-assisted chemical reduction, employing Cu-chlorophyllin as a stabilizing and NaBH<inf>4</inf> as a reducing agent. A vivid red Au0–NPs<inf>CHL</inf> colloidal (7.96 ± 0.29 nm) with a sharp SPR peak at 515 nm was successfully obtained. An aliquot of 75 µL of Au0-NPs<inf>CHL</inf> (0.103 ± 0.03 nmol L−1) and 25 µL of creatinine solution (40 mg L−1) were sequentially loaded into an 8.0 × 0.5 cm cotton swab, separated by a 0.5 cm air gap. Detection began by immersing the swab into Hg2+–contaminated samples for 3 min, allowing Hg2+ adsorption. Breaking the swab generated pressure differential, which, along with gravity, drove the Au0–NPs<inf>CHL</inf> to mix with creatinine. The resulting mixture migrated toward the swab tip by capillary action and reacted with adsorbed Hg2+ through metallophilic 5d10–5d10 interactions. Creatinine acted as a bridging ligand, inducing Au0–NPs<inf>CHL</inf> aggregation and shifting the SPR to 620 nm, causing a visible red-to-blue transition. This sensor enables rapid and visual detection and quantitative evaluation via smartphone RGB analysis. The system demonstrated excellent linearity from 1 to 100 µg L−1 with a low LOD of 0.82 µg L−1. Recoveries of 97.6–101.8 % confirmed high accuracy and minimal matrix interference. The disposable cotton swab RGB sensor provides a rapid, portable, and practical tool for on-site primary assessment of Hg2+ contamination in environmental samples.
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Eco-friendly pectin/BCG film sensor: a smartphone-compatible platform for gamma-aminobutyric acid detection
(2026-05-01)
Niamlaoong, Rungthiwa
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Teerasong, Saowapak
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Phengdaam, Apichat
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Tantirungrotechai, Yuthana
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Wattanasin, Panwadee
This work introduces a biodegradable pectin–bromocresol green (BCG) film integrated into a microplate platform for the colorimetric determination of gamma-aminobutyric acid (GABA). The sensing mechanism relies on electrostatic ion-pair formation between the protonated amine group of GABA (-NH₃+) and the sulfonate group of BCG, producing a distinct color transition from yellow to green. The resulting colorimetric response was quantitatively analyzed using a smartphone-assisted RGB system coupled with ImageJ software. Molecular modelling provided insight into the interaction mechanism and indicated that the GABA-BCG association is dominated by electrostatic interactions. Under optimized conditions, the developed assay exhibited a wide linear range (0.1–1000 mg L−1) with detection and quantification limits of 0.07 mg L−1 and 0.22 mg L−1, respectively. Good analytical precision was achieved (%RSD ≤ 5%), while negligible interference from common amino acids, vitamins and food additives was observed. The method was successfully applied to beverage and dietary supplement samples, demonstrating good agreement with HPLC analysis. The biodegradable BCG–pectin film platform provides a rapid, low-cost, and portable approach for GABA determination and represents a promising sensing strategy aligned with the principles of green analytical chemistry.
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Smartphone RGB camera-based colorimetric platform with double-layer spherical Ca (II)-alginate/ZnONPs hydrogel liquid-core curcumin emulsion for rapid and selective detection of pyridoxine (Vitamin B6) in functional beverages
(2025-08-01)
Chinnawat, Sirinyakorn
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Detsri, Ekarat
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Lerdpiriyaskulkij, Natee
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Teerasong, Saowapak
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Mathaweesansurn, Arjnarong
A portable smartphone-based RGB colorimetric sensor was developed for the quantitative detection of pyridoxine (vitamin B6, VB-6) in functional beverages, employing a novel core–shell hydrogel probe (CUR<inf>Hydrogel</inf>), engineered with a calcium alginate matrix encapsulating a liquid-phase curcumin emulsion and externally layered by poly(diallyl dimethyl ammonium chloride)-functionalized ZnO nanoparticles (ZnONPs/PDADMAC). The CUR<inf>Hydrogel</inf> spheres were fabricated via a molecular self-assembly reverse spherification and demonstrated high mechanical stability (stiffness: 6.45 × 104 N/m, compressive strength: 1.01 × 106 N/m2) along with excellent UV-blocking photostability for up to 28 days. The CUR<inf>Hydrogel</inf> probe was applied for detecting VB-6 via a smartphone-based sensing platform. The colorimetric assay was based on a two-step strategy involving initially the formation of the colorless pyridoxine-boron complex by VB-6 and boric acid, after which the remaining boric acid binds with curcumin to produce a red rosocyanine dye. A higher VB-6 concentration yields less rosocyanine and a discernible color shift from orange to yellow, which is quantified via smartphone RGB analysis. The RGB values were assessed via a smartphone application, providing the linearity of VB-6 detection of 10–125 mg L−1 with LOD and LOQ of 2.93 mg L−1 and 9.77 mg L−1. The CUR<inf>Hydrogel</inf> exhibited excellent precision with relative standard deviations (RSDs) ranging from 0.20 to 0.27 %, while recoveries ranged from 99.84 % to 103.03 %. Particularly, the results of this method were also validated by comparing with HPLC and UV–vis spectrophotometry. The smartphone RGB camera-based colorimetric sensor of CUR<inf>Hydrogel</inf> has great potential application prospects for detecting VB-6 in functional beverage samples.
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A flow-circulation system incorporating a PVP-BiOBr@rGO assembly for simultaneous degradation and detection of oxytetracycline in fish farm wastewater
(2025-05-27)
Teerasong, Saowapak
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Suknakhin, Nichakarn
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Sonsaket, Thanamat
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Teerasong, Wanatchaporn
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Ruttanapun, Chesta
This work focuses on developing a new flow-circulation system for simultaneous detection and degradation of oxytetracycline (OTC) in fish farm wastewater to address a need for antibiotic abatement in wastewater treatment. Polyvinyl pyrrolidone capped bismuth oxybromide assembled with a reduced graphene oxide (PVP-BiOBr@rGO) photocatalyst was solvothermally synthesized and characterized. The prepared photocatalyst exhibited a morphological flower-like structure with a high surface area, 47.59 m2 g−1. Its band gap energy was 2.93 eV. A ternary PVP-BiOBr@rGO composite showed lower charge recombination than its pure form. PVP-BiOBr@rGO was filled inside a catalyst column of a flow system, with a spectrophotometer at the column end. Wastewater was continuously transported through the column and OTC spectrophotometrically examined during its degradation. The wastewater was recirculated until the OTC concentration was minimized. This system achieved 90.3% degradation of OTC within 180 min. The catalyst column could be regenerated for 2 cycles. The proposed flow system offers the advantages of ease of use, inline operation, and real-time sensing. This highlights a potential for real-world sustainable wastewater treatment applications.
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Influence of a Non-ionic Surfactant on the Release of Rhodamine B from Poly(vinyl) Alcohol/Polyoxalate/Span-80 Composite Nanofibers Prepared by Emulsion Electrospinning
(2024-10-26)
Phromviyo, Nutthakritta
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Chompoosor, Apiwat
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Teerasong, Saowapak
Controlling drug release using a nanocomposite method is crucial; however, burst release must be avoided in order to obtain effective controllable drug release. In this study, poly(vinyl) alcohol/polyoxalate/Span-80 (PVA/ POX/ Span-80) composite nanofibers loaded with Rhodamine B were produced using emulsion electrospinning. The objective of this work was to evaluate the cooperative roles of POX and Span-80 on nanofibrous scaffold stability and drug release regulation by monitoring Rhodamine B release performance from electrospun composite nanofibers. The microstructure and hydrophilic properties of the emulsion electrospun nanofibers were studied using scanning electron microscopy (SEM), water contact angle, and swelling tests. According to the results, increasing the POX content had a significant effect on the size of nanofibers. The water contact angles increased as the POX content increased. The release of Rhodamine B was governed by a two-stage diffusion mechanism that was greatly influenced by PVA/POX ratios and Span-80. To compare release behavior, non-emulsion electrospun nanofibers without Span-80 were prepared as control samples. Emulsion nanofibers were found to release at a slower rate than non-emulsion nanofibers. The in vitro release profiles revealed that Rhodamine B was released from emulsion electrospun fibers in a sustainable manner and that no initial burst release was observed. These findings imply that emulsion electrospun nanofibers can potentially be used to deliver drugs, nutraceuticals, and fragrances in a prolonged manner.
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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
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Salungyu, Jirawat
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Teerasong, Saowapak
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Uraisin, Kanchana
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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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