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34. Study on the Rapid Limit Test for Six Sulfonamide Residues in Food Based on the TLC-SERS Method.

Author

Ma, Yukun, Zhang, Min, Li, Li, Liu, Jicheng, Xu, Feng, Wang, Yuanrui, Song, Bo, Xu, Tao, Hong, Yue, and Zhang, Honglian

Subjects
SULFONAMIDE drugs, SILICA gel, AQUATIC animals, FOOD of animal origin, ANIMAL culture
Abstract

Sulfonamides are not only widely applied in clinics but also highly valued in animal husbandry. Recently, it has become common for sulfonamide residues to exceed the standard limits in food, which can affect human health. Current regulations limit these residues. Therefore, we constructed a new limit test method to rapidly determine the levels of sulfonamide residues. Six sulfonamides were detected using the latest method called TLC-SERS, namely, sulfamethasone (A), sulfamethazine (B), sulfadoxine (C), sulfamethoxydiazine (D), sulfamethoxazole (E), and sulfathiazole (F). The optimal conditions for SERS detection were investigated for these six drugs, and the separation effects of different TLC spreaders on them were compared. Then, we successfully established a separation system using dichloromethane–methanol–ammonia in a ratio of 5:1:0.25 (v/v/v), which provided good separation effects on the six drugs. The residues were preliminarily separated via TLC. A silver sol solution was added to the spot on the silica gel G plate at the corresponding specific shift values, and SERS detection was performed. The sample solution was placed on the spot under a 532 nm laser, and the SERS spectrum was collected and analyzed for the six sulfonamides. The results showed obvious variations in the SERS spectrum among the six sulfonamides, with the LODs being 12.5, 6.4, 6.3, 7.1, 18.8, and 6.2 ng/mL from A to F, respectively, and an RSD of <3.0%. Within 48 h, the SERS signal for each sulfonamide drug was kept stable, with an RSD of <3.0%. The detection results of 20 samples using the TLC-SERS method were consistent with those obtained by UPLC-MS/MS. The established TLC-SERS method is simple and fast, providing a useful reference for the rapid detection of residue limits in food. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Metal–support interaction triggered d–p orbital hybridization for efficient electrocatalytic semi-hydrogenation of alkynes.

Author

Wan, Qiong, Zhang, Jiaxun, Liu, Xuan, Li, Huizhi, Abdullah, Ren, Taotao, Liu, Qiyuan, Xu, Yongheng, Liu, Jia, Liu, Jicheng, Yao, Bingqing, Fang, Yiyun, Li, Xinzhe, and He, Chi

Abstract

Semi-hydrogenation of alkynes to alkenes using electrochemical approaches is an appealing alternative to conventional thermocatalytic strategies, as it efficiently utilizes water as the hydrogen source at ambient temperature. However, the precise modulation of atomic and electronic structures of catalytic Pd active sites remains a persistent challenge, particularly in enhancing the conversion yield of alkynes and improving the selectivity of alkenes. Here, we synthesize Pd nanoparticles anchored onto the surface of the defective two-dimensional Fe2O3 support, referred to as Pd/Fe2O3 catalysts, to conduct the electrocatalytic semi-hydrogenation of alkynes. Intriguingly, we observed the reconstruction of the atomic structure and configuration of Pd nanoparticles in the Pd/Fe2O3 catalysts due to metal–support interaction, caused by the hybridization of Pd d and O p orbitals. This interaction significantly weakens the binding strength of Pd sites in the Pd/Fe2O3 catalysts to the chemisorbed 4-aminophenylacetylene and reactive hydrogen intermediates. Consequently, Pd/Fe2O3 catalysts achieve a high conversion rate (99%) and selectivity (99%) in the semi-hydrogenation of 4-aminophenylacetylene coupled with high faradaic efficiency, outperforming both benchmark commercial Pd/C and other reference catalysts. Additionally, terminal alkynes featuring diverse functionalized groups, including those with easily reducible or passivated functionalities, can be efficiently semi-hydrogenated using Pd/Fe2O3 catalysts. [ABSTRACT FROM AUTHOR]

Published
2024
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46. Well-posedness of stochastic variational inequalities with discontinuous drifts.

Author

Xiao, Guangpeng and Liu, Jicheng

Subjects
*DISCONTINUOUS coefficients
Abstract

In this paper, we investigate the well-posedness of stochastic variational inequalities on ℝ d with discontinuous drift coefficients. First, a case that drift coefficients are only integrable on (0 , T) × ℝ d is considered. Utilizing Girsanov's theorem, Zvonkin's transform and Yamada–Watanabe's principle, we derive the weak well-posedness if d > 1 and strong well-posedness if d = 1. Second, if the drift coefficients are piecewise Lipschitz continuous and d = 1 , strong well-posedness is also obtained by virtue of a transform which regularizes the discontinuous drifts. [ABSTRACT FROM AUTHOR]

Published
2024
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