Food Science & Nutrition
·
2019
·Vol. 7
·期 6
·2151-2158
·
IF 1.747
Kai Yang,Cheng Zhou,Zhenhuan Yang,Lan Yu,Ming Cai,Changqing Wu,Peilong Sun
Although sulfites are widely used in shrimp processing, the contents of residual sulfite need to be strictly controlled due to their potential toxicity. In this paper, a novel method was developed for determination of the free and total sulfites in shrimps. Major procedures of the method includes separation of free and total sulfites with ultrasound-assisted extraction and pH adjustment for 20 min, then a precolumn derivatization was conducted by 2,2′-Dithiobis (5-nitropyridine) and verified by LC-MS, and finally HPLC coupled with an ultraviolet (UV) detector was carried out. Results indicated that the UV absorption wavelength shifted from 213 (sulfites) to 320 nm (new disulfide compounds), significantly reducing the interference of natural occurring compounds and solvents in the matrix. The standard curves exhibited a good linear range of 3.2–51.2 mg/L ( R 2 = 0.9996). The limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 1.0 mg/L, respectively. The contents of free and total sulfite in frozen shrimps were 26.58 ± 0.48 and 31.44 ± 0.83 mg/kg calculated by SO 2 , respectively. These were similar ( p > 0.05) to the data obtained by the method of ion chromatography. In conclusion, the new developed method has been proved to be a reliable and economic method for effective determination of free and total sulfites in the shrimps, and the method could be expanded in determination of the sulfites in other food products.
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JOURNAL OF COORDINATION CHEMISTRY
·
2019
·
IF 1.685
Yafang Ge,Guoting Li,Dongxia Fu,Lina Liu,Benlai Wu
Two metal–organic frameworks based on a multifunctional ligand 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid (H3L), [Mn(HL)(C2H5OH)]n (1) and {[Zn(HL)(H2O)2]·H2O}n (2), have been hydro/solvothermally synthesized and characterized by IR, elemental analyses, X-ray powder and single-crystal diffractions, and thermogravimetric analyses. In 1, (HL)2– ligands adopt the μ
3-kN,O:kN′,O′:kN′′ coordination mode and use their imidazoledicarboxylates to bis-chelate MnII into left- and right-handed helixes which are further bridged into a mesolayer structure with (4·82) topology through the coordination of their pyridyl groups. In 2, (HL)2– ligands only use their imidazoledicarboxylates to bis-chelate ZnII into linear chains which are further linked into a 2D supramolecular framework through interchain hydrogen–bonding interactions. Interestingly, the structures of 1 and 2 are mainly dominated by the bis-N,O-chelation of the imidazoledicarboxylate in (HL)2–. As for the formation of the imidazoledicarboxylate-bridged helical chains in 1 or straight chains in 2, it largely depends on the cis- or trans-chelation of two imidazoledicarboxylates around the same metal center. Magnetostructural analysis of 1 discloses that the bis-N,O-chelating imidazoledicarboxylate of (HL)2– transmits antiferromagnetic interactions along the imidazoledicarboxylate-bridged helical chain with the spin-coupling constant of –0.71 cm–1. Additionally, 2 emits greatly enhanced blue fluorescence mainly originating from the intraligand charge transition.
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ACS Omega
·
2018
·
IF 0
Qizhou Dai,Zhuo Zhang,Tingting Zhan,Zhong-Ting Hu,Jianmeng Chen
This study presents a novel spinel-type zinc aluminate nanometer catalyst and is applied in catalytic ozonation for wastewater treatment. The zinc aluminate (ZnAl2O4) catalysts were synthesized by hydrothermal, sol–gel, and coprecipitation methods, and their characteristics were analyzed by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrum, Fourier transform infrared, and X-ray photoelectron spectroscopy (XPS) techniques. 5-Sulfosalicylic acid (SSal) was selected as the typical pharmaceutical and personal care product and used to evaluate the catalytic activity of ZnAl2O4. Compared to ozonation, an obviously higher removal efficiency for the SSal degradation was achieved with the nanocatalyst addition in catalytic ozonation. The removal of SSal and chemical oxygen demand reached 64.8 and 46.2%, respectively, after 60 min in the presence of ZnAl2O4, whereas it was only 49.4 and 33.2%, respectively, in ozonation. The comparison of catalysts showed that the ZnAl2O4 prepared by the hydrothermal method presented a better catalytic activity in ozonation. The effect of radical scavenger experiment results and the characterization of XPS implied that •OH was the main active oxidative species in catalytic ozonation. The reusability results showed that the ZnAl2O4 catalyst possessed a high stability and could be widely used in catalytic ozonation for wastewater treatment.
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APPLIED CATALYSIS A-GENERAL
·
2018
·
IF 4.521
Junmou Du,Huihuang Fang,Hongyan Qu,Jinping Zhang,Xinping Duan,Youzhu Yuan
5-Hydroxymethyl-2-furfural (HMF) is a key platform molecule for biomass utilization. The HMF derivative 2,5-furandicarboxylic acid (FDCA) by oxidation of HMF is a promising alternative for terephthalic acid as a monomer in polyethylene terephthalate. However, due to the facile purification of dimethyl furan-2,5-dicarboxylate (DMFD), an oxidative esterification derivative of HMF, is more desirable. In this work, supported Au–Cu bimetallic catalysts with Au–CuO x ( x = 0–1) nanohybrids were prepared by a reduction–oxidation pretreatment strategy. The as-prepared catalysts were used for the oxidative esterification of HMF into DMFD under base-free conditions using oxygen as sole oxidant. Activity tests showed that the optimized Au–Cu/γ-Al 2 O 3 catalyst displayed a remarkably high DMFD yield of up to 98% and a turnover frequency (TOF) value of 243 h –1 , whereas the monometallic Au and Cu catalysts exhibited poor performance. Various characterizations confirmed the strong interaction between Au nanoparticles and CuO x species, and their synergistic effect on the enhanced performance of HMF oxidative esterification. The reduction–oxidation pretreatment promoted the dispersion of CuO x and intensified the interaction of Au nanoparticles with CuO x . A plausible reaction mechanism for the oxidative esterification of HMF over Au–Cu/γ-Al 2 O 3 was proposed. This work provided new insights into the effect of reduction–oxidation pretreatment on the fabrication of supported Au–CuO x nanohybrids for the production of DMFD by HMF oxidative esterification.
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Catalysis Science & Technology
·
2018
·Vol. 8
·期 23
·6091-6099
·
IF 5.365
Danxin Hu,Hualei Hu,Hao Zhou,Guozheng Li,Chunlin Chen,Jian Zhang,Yong Yang,Yaoping Hu,Yajie Zhang,Lei Wang
The highly efficient selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) was achieved in a fixed-bed reactor by using inexpensive potassium-doped Cu/Al2O3 catalysts, which were prepared via a successive incipient wetness impregnation method. The characterization results revealed that the introduction of potassium could adjust the size of the copper particles and modify the acid–base property of the catalyst, leading to a significant change in its performance for the selective hydrogenation of HMF to BHMF. The highest yield of BHMF (98.9%) was obtained over the 1.5K–Cu/Al2O3 catalyst under the reaction conditions of 120 °C, 2.0 MPa of H2, and a weight hourly space velocity (WHSV) of 1.0 h−1. The excellent performance could be explained by the fact that the addition of an appropriate amount of potassium facilitated the dispersion of copper and reduced the acidity of the catalyst, which improved the catalytic activity and suppressed unwanted side reactions, respectively.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2018
·
IF 3.649
Kai Qiao,Feng Zhou,Zheng Han,Jie Fu,Huixia Ma,Guang Wu
Two series of ZSM-5 catalysts with hierarchical porosity were hydrothermally synthesized by adding two types of organosilane reagents (OSA) into the medial synthesis system. The effects of the types and addition amounts of OSA on the pore characteristics, crystallinity, morphology and acidity of the ZSM-5 zeolites were studied by XRD , SEM, TEM , N 2 -adsorption, 27 Al MAS NMR and NH 3 -TPD. Mesopores were generated by introducing appropriate amounts of OSA. In addition, the catalytic performance of the hierarchical ZSM-5s were investigated for the catalytic fast pyrolysis (CFP) of cellulose . The increase in the mesoporosity leads to a reduced amount of coke. However, the highest yield of aromatics was obtained for the mesoporous sample with the greatest microporosity. Thus, the right balance between meso- and microporosity is critical for achieving high aromatic yields. In addition, the distribution of aromatic products is directly related to the microporosity.
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ANALYTICA CHIMICA ACTA
·
2013
·
IF 4.387
Yufeng Zhang,Shun Xiao,Lijuan Sun,Zhiwei Ge,Fengkai Fang,Wen Zhang,Yi Wang,Yiyu Cheng
A high throughput method was developed for rapid screening and identification of bioactive compounds from traditional Chinese medicine, marine products and other natural products . The system, integrated with five-channel chromatographic separation and dual UV–MS detection, is compatible with in vitro 96-well microplate based bioassays. The stability and applicability of the proposed method was validated by testing radical scavenging capability of a mixture of seven known compounds (rutin, dihydroquercetin, salvianolic acid A , salvianolic acid B , glycyrrhizic acid, rubescensin A and tangeretin). Moreover, the proposed method was successfully applied to the crude extracts of traditional Chinese medicine and a marine sponge from which 12 bioactive compounds were screened and characterized based on their anti-oxidative or anti-tumor activities. In particular, two diterpenoid derivatives, agelasine B and (−)-agelasine D, were identified for the first time as anti-tumor compounds from the sponge Agelas mauritiana , showing a considerable activity toward MCF-7 cells (IC 50 values of 7.84 ± 0.65 and 10.48 ± 0.84 μM, respectively). Our findings suggested that the integrated system of 5-channel parallel chromatography coupled with on-line mass spectrometry and microplate based assays can be a versatile and high efficient approach for the discovery of active compounds from natural products.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2014
·
IF 2.129
Jinhua Zhu,Lanlan Chen,Yingying Dong,Jiazhong Li,Xiuhua Liu
In this work, the interaction of 5-Hydroxymethyl-2-furfural (5-HMF) with calf thymus DNA (ctDNA) under simulated physiological conditions (Tris–HCl buffer of pH 7.40), was explored by UV absorption spectroscopy, fluorescence spectroscopy and molecular modeling method, using ethidium bromide (EB) as a fluorescence probe of DNA. The fluorescence quenching mechanism of EB–ctDNA by 5-HMF was confirmed to be a static quenching, which derived from the formation of a new complex. The binding constants of 5-HMF with DNA in the presence of EB were calculated to be 2.17 × 10 3 , 4.24 × 10 3 and 6.95 × 10 3 L mol −1 at 300, 305 and 310 K, respectively. The calculated thermodynamic parameters, enthalpy change Δ H and entropy change Δ S , suggested that both hydrophobic interactions and hydrogen bonds played a predominant role in the binding of 5-HMF to DNA. According to the UV absorption spectroscopy and melting temperature ( T m ) curve results, the binding mode of 5-HMF with DNA was indicative of a non-intercalative binding, which was supposed to be a groove binding. The molecular modeling results showed that 5-HMF could bind into the hydrophobic region of ctDNA and supported the conclusions obtained from the above experiments.
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Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 9
·4992-4999
·
IF 7.443
Shanshan Yin,Jie Sun,Bing Liu,Zehui Zhang
Magnetic material grafted with acid polyionic liquids was successfully prepared by the radical oligomerization of bis-vinylimidazolium salts on the surface of mercaptopropyl-modified silica-coated Fe3O4, and well characterized by several model technologies. The as-prepared magnetic catalyst (Fe3O4@SiO2–SH–Im–HSO4) showed high catalytic activity for the synthesis of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) and fructose-based carbohydrates. The reaction temperature showed a remarkable effect on EMF yield. High EMF yield of 89.6% was obtained at 100 °C by the etherification of HMF. The one-pot conversion of fructose, sucrose and inulin catalyzed by Fe3O4@SiO2–SH–Im–HSO4 generated EMF with yields of 60.4%, 34.4% and 56.1%, respectively. The catalyst could be readily separated from the reaction mixture by a permanent magnet, and showed high stability in recycling experiments. This study shows a green and sustainable method for the synthesis of value-added liquid fuel from renewable resources.
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CRYSTENGCOMM
·
2014
·Vol. 16
·期 28
·6450-6458
·
IF 3.858
Song Li,Jia-Mei Chen,Tong-Bu Lu
Although polymorphism is a common phenomenon, the polymorphism of co-crystals is not studied extensively as compared to single-component molecules. Herein we report polymorphism in a co-crystal system comprising 5-fluorouracil, and 4-hydroxybenzoic acid with a 1 : 1 stoichiometry. The polymorphs were characterized by single-crystal and powder X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. Crystal structure analysis revealed different synthons of 5-fluorouracil and 4-hydroxybenzoic acid in two forms. The solvent-drop grinding experiments show a high degree of solvent polarity specificity. The theoretical and experimental methods suggest an enantiotropic relationship between the polymorphs.
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TETRAHEDRON
·
2017
·
IF 2.651
Bing Lin,Wen-Hui Zhang,Dan-Dan Wang,Yi Gong,Qi-Di Wei,Xiong-Li Liu,Ting-Ting Feng,Ying Zhou,Wei-Cheng Yuan
Developed herein is a diversity-oriented one-pot multicomponent synthesis of polycyclic 3,3′- pyrrolidinyl-dispirooxindoles 3 via a multicomponent 1,3-dipolar cycloaddition event of 3-methyl-4-nitro-5-isatylidenyl-isoxazoles 2 with azomethine ylides (thermally generated in situ from isatins and proline or thioproline). Products bearing four consecutive stereocenters consist of two oxindole moieties and a polycyclic pyrrolidinyl core, including vicinal spiroquaternary stereocenters fused in one ring structure were smoothly obtained in high yields (up to 85% yield) with good diastereoselectivity (up to >20:1). Valuable features of this method were application of 3-methyl-4-nitro-5-isatylidenyl-isoxazoles as 1,3-dipolarophiles and the design of new hybrid architectures for biological screenings through the adequate fusion of these sub-units of isoxazole and 3,3′-pyrrolidinyl-dispirooxindole, generating drug-like molecules.
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PETROLEUM CHEMISTRY
·
2017
·Vol. 57
·期 3
·209-214
·
IF 0.493
Liu G. L.,Wang Y. D.,Zhang R.,Liu H. Y.,Liu Z. C.,Meng X. H.
The catalytic cracking performance of light hydrocarbon model compounds (1-hexene, n -octane, i -octane, ethylcyclohexane and ethylbenzene) over a mesoporous catalyst based on ZSM-5 zeolite was analyzed and compared using a microscale apparatus with a fixed-bed reactor. The effects of reaction temperature and weight hourly space velocity (WHSV) on feed conversion and the yields of ethene and propene were investigated. The results showed that with increased reaction temperature, the conversion of model compounds increased monotonically, and that of 1-hexene was close to 100% above 660°C; the yield of ethene plus propene of n -octane, i -octane and ethylcyclohexane increased continuously, while that of 1-hexene and ethylbenzene passed through maximum. With increased WHSV, the yield of ethene plus propene of ethylbenzene increased continuously, and that of the other model compounds decreased continuously. Through comprehensive analysis of the data, it is indicated that 1-hexene exhibited the highest cracking performance, followed by n -octane and ethylcyclohexane, whereas i -octane and ethylbenzene exhibited the lowest.
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