Determination of Ascorbic Acid,Total Ascorbic Acid,and Dehydroascorbic Acid in Bee Pollen Using Hydrophilic Interaction Liquid Chromatography-Ultraviolet Detection

Ascorbic acid (AA) is one of the essential nutrients in bee pollen, however, it is unstable and likely to be oxidized. Generally, the oxidation form (dehydroascorbic acid (DHA)) is considered to have equivalent biological activity as the reduction form. Thus, determination of the total content of AA and DHA would be more accurate for the nutritional analysis of bee pollen. Here we present a simple, sensitive, and reliable method for the determination of AA, total ascorbic acids (TAA), and DHA in rape (Brassica campestris), lotus (Nelumbo nucifera), and camellia (Camellia japonica) bee pollen, which is based on ultrasonic extraction in metaphosphoric acid solution, and analysis using hydrophilic interaction liquid chromatography (HILIC)-ultraviolet detection. Analytical performance of the method was evaluated and validated, then the proposed method was successfully applied in twenty-one bee pollen samples. Results indicated that contents of AA were in the range of 17.54 to 94.01 µg/g, 66.01 to 111.66 µg/g, and 90.04 to 313.02 µg/g for rape, lotus, and camellia bee pollen, respectively. In addition, percentages of DHA in TAA showed good intra-species consistency, with values of 13.7%, 16.5%, and 7.6% in rape, lotus, and camellia bee pollen, respectively. This is the first report on the discriminative determination between AA and DHA in bee pollen matrices. The proposed method would be valuable for the nutritional analysis of bee pollen.     

“抑制-萃取”法从含铁酸溶液中选择性提钒

酸法浸出石煤提钒因具有环保、金属收率高的特点而备受关注,但同时进入母液的铁(高含量的Fe³⁺)严重影响了钒的富集和产品生产。 对此,本文提出一种基于“抑制-萃取”效应的钒/铁分离混合萃取体系(P507(2-乙基己基磷酸-单2-乙基己基酯)+ N235(三辛/癸烷基叔胺)+磺化煤油),并详细研究了各因素对钒铁分离和钒富集的影响规律。 结果表明,P507是钒铁萃取的主体,N235不具萃Fe³⁺能力,是产生抑制铁萃取的关键因素,其浓度越高铁萃取率越低;对于酸度较高(pH≤0.4)的原料液钒/铁的分离效果仍较好,这表明了该“抑制-萃取”混合萃取体系对高酸度浸出液钒/铁分离的适用性。 采用氨水从负载有机相中反萃取钒铁,当氨水浓度为6 mol/L时钒的反萃率99%以上,25 ℃,V(有机相)∶V(水相)=2∶1时的反萃液中钒质量浓度14.73 g/L,铁质量浓度小于0.022 g/L,m(V)/m(Fe)=669.5。 该“抑制-萃取”法分离钒/铁操作简单、经济高效,极具工业化前景。     

Novel oxovanadium phosphate tubule incorporating 2,2-bipyridine ligands: hydrothermal synthesis and crystal structure of [(V(IV)O)(3)(mu(5)-PO(4))(2)(2,2'-bpy)(mu-OH(2))].1/3H(2)O

The novel tubular framework of [(V(IV)O)(3)(mu(4)-PO(4))(2)(2,2'-bpy)(mu-OH(2))].1/3H(2)O, which was synthesized from hydrothermal reaction, possesses some attractive structural features: (i) O=V(IV)O(4)(OH(2)) octahedra and PO(4) tetrahedra linked together by corner-sharing and face-sharing into a cylinder-shaped channel including 6 water molecules per cell unit, and (ii) (VO)(2,2'-bpy) groups regularly arranged around the tube, so that the 2,2-bpy ligands constitute an organic shell around an aqueous polar channel.     

毛细管色谱柱快速静态涂渍方法的研究

建立了用丁烷作溶剂的快速静态涂渍法。用此方法制备一根毛细管柱只需４～６小时,操作简单,重复性好,较好地克服了常规静态法制柱时间长、操作复杂两大缺点。它可用于制备不同管径的毛细管柱及交联柱。     

Effect of Ag doping concentration on the electronic and optical properties of anatase TiO2: a DFT-based theoretical study

The electronic and optical properties of pure and Ag-doped anatase TiO₂ have been calculated by spin-polarized density functional theory. Ag-doped TiO₂ with different Ag doping concentrations ranging from 2.08 to 8.33 % was investigated, and the electronic and optical properties evaluated. Substitutional Ag doped at Ti sites introduced Ag 4d states just above the valence-band maximum, which may help in shifting visible-light excited electrons to the conduction band. Our results show that increasing the doping concentration will enhance visible-light absorption up to Ag doping concentration of 6.25 %; however, further increase of the doping concentration leads to a decrease in visible-light absorption. These results indicate the possibility of tailoring the band gap and optical absorption of TiO₂ doped with Ag by varying the doping concentration. The enhanced visible-light absorption for Ag-doped TiO₂ with doping concentration of 6.25 % may be due to the existence of widely distributed Ag 4d states above the valence-band maximum and the optimal doping concentration. Ag doping shifted the absorption edge of TiO₂ towards visible light, consistent with recent experimental results. Our calculation results provide a reasonable explanation for the experimental findings.     

离子色谱柱切换技术同时测定食品中的多种成分

采用离子色谱柱切换技术同时测定了保留性质差别较大的有机酸以及不同价态的无机阴离子。由于柱切换基本不影响色谱基线,该法有较高的灵敏度。同时测定了食品中的乙酸,山梨酸、苯甲酸、糖精、氯离子和磷酸根。     

Pharmacokinetic Study of ZS-1, a Targeted Peptide to NCI-H1299, in Rats Following Intravenous Administration

To investigate the pharmacokinetics of ZS-1 following intravenous injection in rats, ZS-1 was administered at doses of 20, 30 and 45 mg kg^?1, respectively. Blood samples were collected at 0.5, 3, 8, 12, 15, 20, 30, 40 and 45 min. ZS-1 in rat plasma was measured by LC. The limit of detection (LOD) was 0.02 μg mL^?1. The relative standard deviation (RSD) of intra- and inter-day precisions were <10%, and the accuracy of intra- and inter-day were >94%. The mean extraction recovery of ZS-1 was 86.1%. After intravenous injection at doses of 20, 30 and 45 mg kg^?1, the concentration–time curves of ZS-1 fitted well to one compartment model. Area under the concentration–time curves (AUC) increased with dose. Clearance rates (CL) and elimination half-lives (T _1/2) had no significant difference between different dose groups (P > 0.05). ZS-1 was stable in plasma after at 25 °C for 2, 4, 6 h, after three freeze–thaw cycles, after ?20 °C for a month, and after ?80 °C for 3 months. The accuracy of ZS-1 was between 96.8 and 106.9%. The results indicated there was no significant degradation. These data indicated that the method for analysis of ZS-1 was reliable and the pharmacokinetic data could guide dosing regimens to be tested in future clinical pharmacokinetic study.     

Light harvesting in microscale metal-organic frameworks by energy migration and interfacial electron transfer quenching

Microscale metal-organic frameworks (MOFs) were synthesized from photoactive Ru(II)-bpy building blocks with strong visible light absorption and long-lived triplet metal-to-ligand charge transfer ((3)MLCT) excited states. These MOFs underwent efficient luminescence quenching in the presence of either oxidative or reductive quenchers. Up to 98% emission quenching was achieved with either an oxidative quencher (1,4-benzoquinone) or a reductive quencher (N,N,N',N'-tetramethylbenzidine), as a result of rapid energy migration over several hundred nanometers followed by efficient electron transfer quenching at the MOF/solution interface. The photoactive MOFs act as an excellent light-harvesting system by combining intraframework energy migration and interfacial electron transfer quenching.     

Synthesis of HZSM-5 zeolites with excellent DME aromatization properties by orthogonal test

Abstract

The synthesis conditions of HZSM-5 zeolite, including crystallization temperature, crystallization time and raw material ratio, were investigated by L₃₂ (4⁸) orthogonal test to specifically optimize its performance in dimethyl ether (DME) aromatization for the first time. Based on the total yield of aromatic products, the synthesis conditions of HZSM-5 zeolite with the best DME aromatization properties were obtained by comprehensive analysis and validation experiments. The relationship between the aromatization performance, crystalline structure, pore structure, and acidity of HZSM-5 zeolite were analyzed. The results showed that the HZSM-5 zeolite accompanied by hierarchical structure, an appropriate Brønsted and Lewis acid content and uniform crystal morphology, was successfully synthesized under optimized conditions. Over this unmodified and un-doped catalyst, the conversion of DME approached to 99.3% and the total yield of aromatics reached was 53.5%.     

Vacancy‐Rich Ni(OH)2 Drives the Electrooxidation of Amino C−N Bonds to Nitrile C≡N Bonds

Electrochemical synthesis based on electrons as reagents provides a broad prospect for commodity chemical manufacturing. A direct one‐step route for the electrooxidation of amino C?N bonds to nitrile C≡N bonds offers an alternative pathway for nitrile production. However, this route has not been fully explored with respect to either the chemical bond reforming process or the performance optimization. Proposed here is a model of vacancy‐rich Ni(OH)₂ atomic layers for studying the performance relationship with respect to structure. Theoretical calculations show the vacancy‐induced local electropositive sites chemisorb the N atom with a lone pair of electrons and then attack the corresponding N(sp³)?H, thus accelerating amino C?N bond activation for dehydrogenation directly into the C≡N bond. Vacancy‐rich nanosheets exhibit up to 96.5 % propionitrile selectivity at a moderate potential of 1.38 V. These findings can lead to a new pathway for facilitating catalytic reactions in the chemicals industry.