Identification of Geometrical Isomers and Comparison of Different Isomeric Samples of Astaxanthin

Abstract: A high‐performance liquid chromatographic (HPLC) analysis system for isomeric astaxanthin was developed. The separation system consisted of a C₃₀ column and an elution system of methanol/MTBE/water/dichloromethane (77 : 13 : 8 : 2, v/v/v/v). Using the combination of HPLC diode array detector and HPLC atmospheric pressure chemical ionization mass spectrometry, 11 geometrical isomers and 4 epoxides of astaxanthin were successfully identified. Referred to crystal, only isomerization with different degrees was found for solvent dissolving and iodine catalysis, while melting of astaxanthin caused isomerization, slight oxidation, and more noticeable polymerization confirmed by gel permeation chromatography. Chemical changes in isomeric samples all caused a decrease in UV content. The vibrational spectra (infrared and Raman) showed that epoxide was the only new functional group generated for melting. Changes of several key bands and formations of new bands were found in iodine catalysis and melting samples because of isomerization. Practical Application: Eleven geometrical isomers and 4 epoxides, which were normally generated for solvent dissolving, iodine catalysis, and melting of astaxanthin, have been identified by C₃₀‐HPLC‐MS technology. Furthermore, different samples were measured by gel permeation chromatography, UV, infrared, and Raman, based on the analysis of messages, the effect of each processing was well understood.     

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.     

马来酸酐和富马酸对聚丁二酸丁二酯的改性研究

在聚丁二酸丁二酯(PBS)分子主链中添加带有不饱和键的马来酸酐(MAH)和富马酸(FA)单体,得到了含有不饱和键的,具有顺、反结构的PBS基共聚物。通过广角X射线衍射、热重分析、差示扫描量热分析和拉力测试等分析手段,研究了不同结构共聚物的性能。结果表明,随着MAH和FA含量的增加,两种改性后的PBS基共聚物的晶粒尺寸减小;玻璃化转变温度都有所降低;共聚物的热稳定性都略有降低,但高于300℃,仍具有良好的热稳定性;共聚物的拉伸强度差异较大,但断裂伸长率明显提高。在PBS主链中形成顺、反结构的两种单体的添加对PBS基共聚物性能的影响没有太大差别。     

Investigation of kinetics of 4‐methylpentene‐1 polymerization using Ziegler–Natta‐type catalysts

The kinetics of 4‐methylpentene‐1 (4MP1) polymerization by use of Ziegler–Natta‐type catalyst systems, M(acac)₃‐AlEt₃ (M = Cr, Mn, Fe, and Co), are investigated in benzene medium at 40°C. The effect of various parameters such as Al/M ratio, reaction time, aging time, temperature, catalyst, and monomer concentrations on the rate of polymerization and yield are examined. The rate of polymerization increased linearly with increasing monomer concentration with first‐order dependence, whereas the rate of polymerization with respect to catalyst concentration is found to be 0.5. For all cases, the polymer yield is maximum at an Al/M ratio of 2. The activation energies obtained from linear Arrhenius plots are in the range of 25.27–33.51 kJ mol^?1. It is found that the aging time to give maximum percentage yield of the polymer varies with the catalyst systems. Based on the experimental results, a plausible mechanism is proposed that envisages a free‐radical mechanism. Characterization of the resulting polymer product, for all the cases, through FTIR, ¹H‐NMR, and ¹³C‐NMR studies, showed isomerized polymeric structures with 1,4‐structure as dominant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2468–2477, 2003     

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。     

Quantitative determination of monoglycerides and diglycerides by high-performance liquid chromatography and evaporative light-scattering detection

Neutral lipid classes were separated with normal-phase high-performance liquid chromatography, and mono- and diglycerides were determined with an evaporative light-scattering detector (ELSD). The 1,3-diacylglycerols were resolved from the 1,2-diacylglycerol positional isomers, although some 1,3-diacylglycerols of low molecular weight interfered with the 1,2-diacylglycerols of high molecular weight. For monoglycerides, the separations between 1-(and 3-)acyl and 2-acylglycerols were optimized only between those pairs with identical fatty acyl groups. Samples were dissolved in a solvent mixture and analyzed without derivatization. The results (monoglyceride) obtained from this method agreed well with those derived from gas chromatographic and supercritical fluid chromatographic methods. The universal nature of the ELSD makes this method applicable to oils and emulsifiers containing both saturated and unsaturated fatty acyl moieties.     

Impact of composition on the performance of sodium linear alkylbenzenesulfonate (NaLAS)

Like other commercial surfactants, commercial linear alkylbenzenesulfonate is not a single compound but a mixture of components. This mixture comprises different carbonchain homologs, different phenyl isomers, and, in addition, the manufacturing co-product, dialkyltetralin sulfonate. Current manufacturing technology makes it possible to easily vary the average carbon chainlength. On the other hand, the phenyl isomer distribution and dialkyltetralin sulfonate content can be changed only within a certain range. Each of these variations in composition affects performance. This study reports on the effect of commercial alkylbenzenesulfonate composition on surface tension, solubility, viscosity, foam stability, and detergency. The study shows that average carbon chainlength affects all performance properties. Phenyl isomer distribution and dialkyltetralin sulfonate content affect only solubility and viscosity. Presented May 1, 1996, at the Annual Meeting of the American Oil Chemists’ Society, Indianapolis, Indiana.     

多产异构烷烃的催化裂化工艺的工业应用

多产异构烷烃的催化裂化工艺(MIP工艺)是具有我国自主知识产权的生产清洁汽油组分的技术。高桥石化分公司炼油厂1．4Mt／a催化裂化装置按该工艺的要求进行改造，于2002年2月4日进行了工业运转。该装置一直保持平稳运转，操作难度与FCC工艺相当。试验标定结果表明，与现有的催化裂化工艺相比，MIP工艺不仅优化了产物分布，干气和油浆产率分别下降了0．41个百分点和0．99个百分点，液体收率增加了1．17个百分点，而且所生产的汽油荧光法分析的烯烃含量下降约14．1个百分点，饱和烃(主要是异构烷烃)含量增加约12．9个百分点，其中异构烷烃含量大于70％，硫含量下降26．5％，诱导期增加，汽油的RON下降而MON增加，总的抗爆指数基本不变。     

C180异构体分子的半经验量子化学分析

为了研究碳富勒烯异构体的电子结构、稳定性与物理化学特性,本文采用AM1半经验量子力学方法,计算了线形3C60聚合体,三角形3cm聚合体、以及C180富勒烯等三种C180分子的几何构型、电子结构、分子能量以及疏水常数、极化率、折射率与偶极矩,然后,根据计算结果,分析了三种C180异构体分子的化学稳定性与物理化学特性。研究结果表明,三种分子的形成均为吸热,线形3C60聚合体、三角形3C60聚合体的稳定性相当,而C180富勒烯分子具有较好的稳定性。