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A pervaporation-flow injection (PFI) method was developed for the determination of sulfite in selected food samples using a copper hexacyanoferrate-carbon nanotube (CuHCF-CNT)-modified carbon paste electrode. The electrochemical behavior of the modified electrode was observed using cyclic voltammetry in comparison to a CuHCF-modified carbon paste electrode and a bare carbon paste electrode at a scan rate of 100mVs(-1) in 0.10M KNO(3). The bare carbon paste electrode gave the lowest response to sulfite, while the presence of CuHCF made the detection of sulfite possible through electrocatalytic oxidation by the hexacyanoferrate in the modified electrodes. The presence of CNT in the CuHCF-CNT-modified sensor gave the most remarkable current for the detection of sulfite and was then used as a working electrode in the amperometric flow-through cell in the pervaporation flow injection system. The PFI method involves the injection of a standard or sample sulfite solution into a sulfuric acid donor stream to generate sulfur dioxide gas and evaporate into the headspace of the pervaporation unit. The sulfur dioxide diffuses through the PTFE hydrophobic membrane into a potassium nitrate acceptor stream and reverts to the sulfite form, which, subsequently, is transported to the electrochemical flow cell where it is analyzed amperometrically at a CuHCF-CNT-modified electrode at +0.55V (vs. Ag/AgCl). The detection was determined to be applicable in the sulfite concentration range of 0.5-50mgL(-1). The sensitivity, detection limit, and sample throughput were determined to be 2.105nALmg(-1), 0.40mgL(-1) and 11h(-1), respectively. The developed PFI method, coupled with the CuHCF-CNT-modified carbon paste electrode, was applied in the determination of sulfite content in sulfite-containing food products. The results agreed well with those obtained through the officially recommended differential pulse polarographic method.
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http://dx.doi.org/10.1016/j.talanta.2010.03.043 | DOI Listing |
PNAS Nexus
September 2025
Department of Materials Science and Engineering, Westlake University, Hangzhou 310030, PR China.
Uniform dispersion of carbon nanotubes in a polymer matrix is a prerequisite for high-performance nanotube-based composites. Here, we report an in situ polymerization route to synthesize a range of phenolic composites with high loading of single-wall carbon nanotubes (SWCNTs, >40 wt%) and continuously tunable viscoelasticity. SWCNTs can be directly and uniformly dispersed in cresols through noncovalent charge-transfer interactions without the need for surfactants, and further concentrated before in situ polymerization of the solvent molecules, yielding phenolic composites in the forms of conductive pastes, highly stretchy doughs, and hardened solids with high nanotube loading and much enhanced electrical conductivity (up to 2.
View Article and Find Full Text PDFEnviron Res
September 2025
Key Laboratory of Green Utilization of Critical Non-metallic Mineral Resources, Ministry of Education, Wuhan University of Technology, Wuhan, Hubei 430070, China; School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, China. Electronic address: yubiao
In order to promote the development and application of low-carbon cement varieties and the recycling of industrial solid waste, this study used iron tailings and fluorogypsum to prepare iron-rich belite-sulfoaluminate cement (I-BCSA). The suitable conditions for the preparation of I-BCSA in this system were with an excessive addition of 6 wt% of SO in the raw meal, at a calcination temperature of 1250 °C for 1.5 h, and an added-gypsum content of 15 wt%.
View Article and Find Full Text PDFMikrochim Acta
September 2025
National Research and Development Institute for Chemistry and Petrochemistry ICECHIM, 202 Splaiul Independentei Street, 060021, Bucharest, Romania.
Molecular recognition and determination of vascular cell adhesion molecule-1 (VCAM-1), interleukin-6 (IL-6), and natriuretic peptide C-type (NPPC) are essential for the early prognosis and diagnosis of cardiovascular diseases, especially in young obese populations. Highly sensitive and selective devices characterized by low Limits of quantification are required for their determination in whole blood. Therefore, a 3D stochastic sensor was developed by immobilizing a chitosan hydrogel onto a carbon paste electrode (used as the support matrix for the hydrogel), which was subsequently modified with gold nanoparticles, multi-walled carbon nanotubes, and β-cyclodextrin (β-CD/AuNPs@MWCNT/CS/CPE).
View Article and Find Full Text PDFColloids Surf B Biointerfaces
August 2025
School of Stomatology, Qingdao University, Qingdao 266023, PR China; Department of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao 266003, PR China.
White spot lesions (WSLs) are the most common complication of orthodontic treatment, compromising dental health and significantly affecting aesthetics. To address this clinical challenge, this study aims to develop a dual-functional therapeutic strategy that simultaneously promotes the remineralization of demineralized enamel and inhibits the activity of cariogenic bacteria, thereby achieving effective prevention and treatment of WSLs. A hollow double-shell structured CuO@N/C nanozyme (H-CuO@N/C) was synthesized using a one-step hydrothermal method.
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