Nucleosil Chiral-2 and Chiral-3手性柱在分离某些高效芳氧苯氧基丙酸酯类除草剂光学异构体中的应用

用实例叙述了Nucleosil Chiral-2和Chiral-3手性柱在分析某些高效芳氧苯氧基丙酸酯类除草剂光学异构体中的应用,说明了首选Chiral-3手性柱的理由,因为使用Chiral-2柱,上述除草剂的S．异构体（无效体）小峰往往出现在R-异构体（高效体）大峰的拖尾处,而不能被完全分离;使用Chiral-3手性柱,S-异构体小峰出现在R-异构体大峰前,而无此弊病。Chiral-2和Chiral-3手性柱也适用于苯氧丙酸类除草剂光学异构体的分离。     

基于高场非对称离子迁移谱的糖类异构体分离研究

本工作研发了一款配套滤波算法及重叠峰分离算法、可独立使用的平板型高场非对称离子迁移谱(FAIMS)系统,能够在分离不同离子、有效滤噪的同时,从重叠峰中准确、快速提取分析物峰,由此实现物质的精准定性分析。通过评估该FAIMS装置对糖类异构体的分离效果,发现FAIMS能有效分离出蔗糖离子的2种结构,证明其对离子结构差异更加敏感。采用氮气、氦气的混合气体作为载气,可进一步提高FAIMS的分辨力。当氦气比例达到40%时,蔗糖峰和麦芽糖峰的重合度由纯氮气时的77%降低至50%。本研究表明,该FAIMS系统可为同分异构体的定性分析提供一种新方法。     

基于离子淌度-质谱技术分析小分子代谢物的研究进展

近年来,不同原理的离子淌度技术相继出现,与质谱技术相结合已广泛应用于许多领域。在小分子代谢物分析中,氨基酸的手性识别、聚糖的结构解析、脂质的结构表征和类固醇的分析十分重要,但由于小分子代谢物化学性质迥异,且普遍存在同分异构现象,增加了分析难度。离子淌度-质谱(IM-MS)技术为复杂基质中小分子代谢物的快速分离和分析提供了新思路,根据离子的质荷比、碰撞截面积(CCS)和结构信息,可快速区分、表征小分子代谢物及其同分异构体。本文介绍了离子淌度-质谱(IM-MS)的主要类型及其在小分子代谢物分析中的应用情况和存在的不足,并展望其发展前景。     

C30-HPLC-PDA分离与鉴定β,β-胡萝卜素几何异构体

在装备了二极管阵列(PDA)检测器的HPLC上,应用C30固定相,β,β-胡萝卜素的几何异构体获得了良好的分离。分离条件为:固定相=YMCCarotenoidS-5(4.6×250mm)柱;流动相A=乙腈:甲醇:三乙胺(75:25:0.05,V/V);流动相B=甲基叔丁基醚(MTBE)-三乙胺(100:0.05,V/V);线性梯度:B在20min内由0%增至80%;流速=1.0ml/min;PDA波长范围=260～700nm;进样量=20μl。根据各组分的色谱行为、光谱特征和在碘催化下发生几何异构的产物分析,13,13’-、11,11’-、9,9’-顺式和全反式异构体被鉴定。本项研究的结果奠定了应用C30-HPLC-PDA定量检测β,β-胡萝卜素的几何异构体的基础。     

酶法拆分制备共轭亚油酸功能单体

研究利用Lipase AYS催化甲醇和共轭亚油酸(CLA)进行酯化反应,以期对共轭亚油酸异构体进行拆分制备共轭亚油酸功能单体。通过考察酯化反应的影响因素,确定了最优反应条件为:Lipase AYS加酶量180 U/g,反应温度40℃,CLA与甲醇摩尔比1∶1,缓冲液p H 6.5。在最优条件下反应8 h,总酯化率为49.5%,分离产物可以得到甲酯相与脂肪酸相,甲酯相中c9,t11-CLA甲酯的拆分效率达到86.2%,脂肪酸相中t10,c12-CLA的拆分效率达到80.0%,两者回收率分别为72.4%和54.2%。     

二步法制备稀有人参皂苷Rh1组异构体

本论文以制备人参皂苷Rh1为目标,选择三醇类人参皂苷Re为底物,采用酶转化和金属离子催化联用的二步法催化转化,研究了各步骤中的催化反应条件,并对产物进行了纯化和组成分析。结果表明:Absidia sp. P39r菌株产酶能催化转化Re生成Rg1,确定其最佳反应条件为:缓冲液pH5.0,反应温度40 ℃,底物浓度1.2%,反应时间16 h,乙醇浓度10%,在此反应条件下得到的Rg1质量分数最高,为70.5%。然后以Rg1为底物,确定在乙醇-水体系下Fe3+的催化反应产物20(S,R)-Rh1的质量分数最高,催化反应条件优化结果为:乙醇浓度50%,反应温度50 ℃,底物浓度1.7%,Fe3+溶液反应浓度1.4 mol/L,反应时间14 h,20(S,R)-Rh1的质量分数高达61.83%,Rk3、Rh4的质量分数之和为27.34%。在上述条件下将20 g人参皂苷Re与酶液反应,反应结束后用AB-8大孔吸附树脂分离干燥得到含有Rg1的产物14.1 g。再取10.2 g反应得到的Rg1与Fe3+溶液反应,干燥后最终得到的人参皂苷Rh1组异构体质量为8.18 g,得率为80.2%,其中20(S)-Rh1,20(R)-Rh1,Rk3和Rh4的含量分别为37.71%,24.12%,7.27%,20.07%。     

应用C30-HPLC-PDA-ELSD估算番茄红素顺式异构体吸光系数

由于参比样品的匮乏,番茄红素顺式异构体的吸收光谱定量需基于其吸光系数.采用C30-HPLC-PDA-ELSD系统,参照已公布的全反式异构体的吸光系数(A1%1cm=3 400),根据其光谱峰面积与质量峰面积之比,估算出9,9'-顺式异构体、11,11'-顺式异构体和13,13'-顺式异构体的吸光系数分别为2 100、1 819和1 134.这一结果揭示了番茄红素分子中的顺式异构位置、最大吸收波长(λmax)处的吸光系数与顺式峰相对峰高之间的关系,奠定了在C30-HPLC上定量顺式异构体的基础,具有显著的应用价值.在方法上,尝试使用在线串联光谱和质量检测器测定目标化合物的吸光系数.     

Novel Azocoumarin Derivatives—Synthesis and Characterization

The paper presents synthesis and characterization of nine new thiazolyl-(phenyldiazenyl)-2H-chromen-2-one dyes. The impact of substituent structure in thiazole ring in the synthesized azocoumarin derivatives on electrochemical properties, photoisomerization process and photovoltaic response was examined. The dyes were electrochemically active and undergo reduction and oxidation processes. They showed low electrochemically estimated energy band gap in the range of 1.71–2.13 eV. Photoisomerization process of the synthesized molecules was studied in various solvents such as ethanol, chloroform and N,N-dimethylformamide (DMF) upon the UV illumination. It was found that novel azodyes showed reversible trans-cis-trans isomerization and exhibited long thermal back to the trans form, that was even 7 days in DMF. Selected azocoumarin were molecularly dispersed in polystyrene for preparation of guest-host azopolymer systems to study the cis-trans thermal isomerization of obtained dyes in solid state. The photovoltaic activity of the azochromophores was tested in bulk-heterojunction solar cells. They acting as weak donors in device with structure ITO/PEDOT:PSS/dye:PC70BM/Al. No photovoltaic response of cells with azocoumarin derivatives bearing 4-fluorobenzene, 3,4-dichlorobenzene, or 4-(1-adamantyl) unit was found. Additionally, dye which showed the best activity was examined in three-component solar cells ITO/PEDOT:PSS/PTB7:PC70BM:dye/PFN/Al.     

High resolution 13C NMR spectroscopy of rendered animal fats: degree of saturation of fatty acid chains and position on glycerol

This work describes the application of high resolution ¹³C nuclear magnetic response (NMR) to the study of fatty acid composition in animal fats. It allows both the proportions of saturated, mono- and polyunsaturated fatty acid chains and the positional isomerism on glycerol to be determined. Olefinic carbon shifts gave quantitative information on the distribution of saturated, mono- and polyunsaturated fatty acid chains in animal fat triglycerides. Carbonyl carbon shifts gave information about the degree of saturation of fatty acid chains and their positions on the glycerol. The NMR values agree with the results from gas chromatographic analysis.     

Simultaneous determination of dinitrophenol isomers with electrochemical method enhanced by surfactant and their mechanisms research

This paper has adopted a fast and convenient analytical technique to detect dinitrophenol isomers directly and simultaneously. In 0.1 mol L⁻¹ HAc-NaAc buffer solution (pH 5.8), 2,4- and 2,5-dinitrophenol exhibited good resolution by DPV at the GC electrode. By using the surfactant of cetyl trimethyl ammonium bromide, the reduction peaks currents were enhanced and the detection sensitivity was improved dramatically. The action mechanism was investigated in detail and some valuable message has been found. The linear calibration ranges from 1.0 × 10⁻⁶ to 8.0 × 10⁻⁴ mol L⁻¹ for both 2,4- and 2,5-dinitrophenol, with detection limits of 2.4 × 10⁻⁷ for 2,4- and 1.5 × 10⁻⁷ mol L⁻¹ for 2,5-dinitrophenol. This method was applied in the determination of dinitrophenol isomers in model water sample, and the recovery was from 98% to 103%.