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A portable and stable dry starch-KI sensor for headspace iodine vapor detection: A green approach for sensitive ascorbic acid quantification in colored juices
(2025-03-01)
Paojinda, Ananya
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Sribunpeng, Tanaporn
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Kongsatjaviwat, Aumpika
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Kusumaningtyas, Nadia Mira
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Nuihuaykaew, Pichayaporn
This study introduces a stable and portable dry starch-KI paper sensor for detecting iodine vapor in the headspace of a microwell plate, enabling sensitive quantification of ascorbic acid (AA) in colored fruit and vegetable juices. The method leverages the reaction between AA and potassium iodate (KIO<inf>3</inf>) to generate iodine vapor, producing a strong colorimetric response upon interaction with the starch-KI coating. The sensor maintains consistent color intensity for up to 90 min, ensuring reliable on-site analysis. Uniformity testing of 96-spot absorbance for 0.5 mM AA across three batches (n = 3) yielded a mean absorbance of 0.264 ± 0.016 with a %RSD of 6.1 %. Stability assessments at three AA concentrations produced %RSD values of 9.4 %, 5.0 %, and 5.1 %, respectively. The microwell plate format facilitates rapid analysis with minimal sample preparation, effectively minimizing interference from juice color and matrix effects. The sensor demonstrated a linear detection range of 0.1–0.75 mM (r2 = 0.9942) with an LOD of 0.05 mM. Application to fresh juice samples yielded a %recovery of 80–120 % (n = 13). This approach addresses critical challenges such as stability, portability, and matrix interference by effectively separating analytical signals from juice pigments. With a high AGREE score of 0.7, reflecting strong alignment with green analytical chemistry principles, this innovative method offers a practical, eco-friendly solution for on-site AA quantification in nutritional analysis.
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Application of functionalized multi-walled carbon nanotubes supporting cuprous oxide and silver oxide composite catalyst on copper substrate for simultaneous detection of vitamin B2, vitamin B6 and ascorbic acid
(2017-07-01)
Puangjan, Apinya
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Chaiyasith, Suwan
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Taweeporngitgul, Wipawee
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Keawtep, Jeerunda
A new electrochemical sensor was fabricated from chemically functionalized multiwall carbon nanotubes and electrochemically deposited cuprous oxide and silver oxide composite over the nanotubes on copper substrate. The structural, functional, morphological, electrical properties and elemental composition of the composite were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy, field transmission electron microscopy, electrochemical impedance spectroscopy and energy dispersive X-ray spectroscopy. The developed sensor exhibited excellent electrochemical catalytic activity toward oxidation of vitamin B<inf>2</inf> (VB<inf>2</inf>), ascorbic acid (AA) and vitamin B<inf>6</inf> (VB<inf>6</inf>). Compared to the performance of simple copper substrate, that of the modified electrode was greatly superior. This can be attributed to its robust structure, excellent conductivity and large surface area. With a simple electrode that relies on linear diffusion at the surface, an electrochemical analytical method may have a selectivity problem, i.e., various species present in the target medium may oxidize or reduce at potentials not very different from each other. The conducting porous layer of our modified electrode alters this diffusion characteristic to one of approximately ‘thin layer’ that facilitates better discrimination between species. In this work, differential pulse voltammetry was used for simultaneous determination of VB<inf>2</inf>, AA and VB<inf>6</inf>. The linear ranges were 0.05–1752.65 μM, 0.05–1628.54 μM and 0.02–1056.12 μM, and the detection limits (S/N = 3) were 0.014 μM, 0.011 μM and 0.008 μM, respectively. In addition to its high performance, this inexpensive sensor is perfectly stable for simultaneous determination of these species in real samples.
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Electrochemical sensor based on PANI/MnO2-Sb2O3 nanocomposite for selective simultaneous voltammetric determination of ascorbic acid and acetylsalicylic acid
(2016-12-01)
Puangjan, Apinya
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Chaiyasith, Suwan
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Wichitpanya, Saniporn
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Daengduang, Sirirat
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Puttota, Silarin
A new electrochemical sensor made from nanocomposite of manganese dioxide (MnO<inf>2</inf>)-antimony trioxide (Sb<inf>2</inf>O<inf>3</inf>) was fabricated on polyaniline (PANI) - patterned fluorine doped tin oxide (FTO) electrode (PANI/MnO<inf>2</inf>-Sb<inf>2</inf>O<inf>3</inf> nanocomposite/FTO) through a simple potentiostatic deposition method. The properties of the nanocomposite were characterized by field emission scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy and other electrochemical techniques. Such nanostructure combines the advantages of PANI (high conductivity and stability) with that of electrocatalytic species (good electrochemical activity). The sensor was applied for simultaneous determination of ascorbic acid (AA) and acetylsalicylic acid (ASA). The linear relationships between their current intensity and concentration were in the range of 6–265.42 nmol L− 1 and 1.2–228.68 nmol L− 1 with detection limit (S/N = 3) of 1.05 nmol L− 1 and 0.20 nmol L− 1, respectively. Experimental results demonstrated that the sensor possesses high selectivity and suffers no interference from competing species. Moreover, it successfully detected AA and ASA in human urine samples with highly satisfactory results.
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Changes in ascorbic acid, total polyphenol, phenolic acids and antioxidant activity in juice extracted from coated kiew wan tangerine during storage at 4, 12 and 20°c
(2010-03-01)
Puttongsiri, Tongchai
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Haruenkit, Ratiporn
The aim of this research was to investigate changes in ascorbic acid, total polyphenol, phenolic acids and antioxidant activity in juice extracted from Kiew Wan tangerines (Citrus reticulate Blanco cv. Kiew Wan) coated with shellac. The coated fruits were stored for five weeks at 4, 12 and 20°C and samples were taken weekly for analysis. Ascorbic acid decreased during storage at all tested temperatures. The major phenolic acids found were ferulic acid followed by sinapic, caffeic and p-coumaric acid. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2 azinobis (3-ethylbenzothiazoline-6-sulfonate (ABTS) antioxidant activities increased during storage and were correlated with total polyphenol and phenolic acid contents. Sinapic, caffeic and p-coumaric acid levels were significantly correlated with the DPPH while ferulic acid was correlated with the ABTS. All phenolic acids increased during the early stage of storage at 4 and 12°C but decreased at the end. Weight loss of coated fruit during storage was in the range of 4-17%.
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Comparison of some biochemical characteristics of different citrus fruits
(2001-08-29)
Gorinstein, Shela
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Martín-Belloso, Olga
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Park, Yong Seo
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Haruenkit, Ratiporn
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Lojek, Antonin
The goal of this investigation was to evaluate the antioxidant properties of some citrus fruits. The contents of dietary fibre, total polyphenols, essential phenolics, ascorbic acid and some trace elements of lemons, oranges and grapefruits were determined and compared with their total radical-trapping antioxidative potential (TRAP). There were no significant differences in the contents of total, soluble and insoluble dietary fibre in the studied peeled fruits or their peels. The contents of total, soluble and insoluble dietary fibre in peels were significantly higher than in peeled fruits (P < 0.05 in all cases). The peeled lemons, oranges and grapefruits contain 164±10.3; 154±10.2 and 135±10.1 and their peels 190±10.6; 179±10.5 and 155±10.3 mg/100 g of total polyphenols, respectively. The content of total polyphenols in peeled lemons and their peels was significantly higher than in peeled oranges and grapefruits and their peels, respectively. The content of total polyphenols in the peels was significantly higher than in peeled fruits (P < 0.05 in all cases). The same results were obtained in the investigation of essential phenolics and ascorbic acid. The content of Fe in peeled lemons and their peels was significantly higher than in peeled oranges and grapefruits and their peels, respectively. Also the TRAP was significantly higher in peeled lemons and their peels than in peeled oranges and grapefruits and their peels, respectively. In all three fruits, the TRAP was significantly higher in peels than in peeled fruits (P < 0.05). In conclusion, lemons possess the highest antioxidant potential among the studied citrus fruits and are preferable for dietary prevention of cardiovascular and other diseases. The peels of all citrus fruits are rich in dietary fibres and phenolic compounds and suitable for industrial processing. © 2001 Elsevier Science Ltd. All rights reserved.

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