New evaporative light scattering detector for high temperature gel permeation chromatography

A new evaporative light scattering detector (ELSD) for the analysis of polyolefins by high temperature gel permeation chromatography (GPC) was recently introduced by Agilent Technologies. For the first time, we investigated the possibility to use this detector to measure the molecular weight distributions (MWD) of different type of polyolefines (polypropylene, linear, and low-density polyethylene). These samples were previously characterized by GPC with a differential refractive index (DRI) detector by several companies, in an interlaboratory study conducted by International Union of Pure and Applied Chemistry.^[1 Luruli, N. 2010. PHASE 1: IUPAC SEC/GPC Round Robin Project Report: Repeatability and Reproducibility of Sample Preparation and Analysis in High-Temperature SEC, http://media.iupac.org/projects/2005/2005-011-3-400_rpt-phase1_110510.pdf [Google Scholar]^] The excellent baseline stability of ELSD as compared with DRI was reflected in a better reproducibility of the measured average molecular weights. More importantly, after applying required corrections to linearize the response of the ELSD as a function of concentration, we obtained similar results as previously obtained with DRI for the MWD of analyzed resins, covering typical applications of polyolefins.     

Rapid analysis of triterpenic acids by liquid chromatography using porous graphitic carbon and evaporative light scattering detection

An original system which uses Porous Graphitic Carbon as support and a mixture of organic solvents as mobile phase is proposed for the analysis of triterpenic acids by liquid chromatography. The separation of betulinic acid, ursolic acid, oleanolic acid, and 18alpha- and 18beta-glycyrrhetinic acids was carried out within a short time and monitored by evaporative light scattering detection as universal detection method. Molecular modelling studies show that the main contribution to the selectivity comes from the electrostatic interaction characterised by the dipole moment of the products.     

基于非线性冗余算法的凝汽器状态评价

凝汽器状态评价指标是具有不同量纲的特征参数,为避免对具有不同量纲的特征空间实施无量纲化变换造成的信息失真,隶属度转换模式成为凝汽器状态评价的基本模式.由于特征参数状态渐变连续,所以表征参数状态的指标隶属度是模糊隶属度.模糊隶属度表征模糊状态,模糊隶属度转换实现模糊状态转换.用冗余理论界定模糊隶属度转换的非线性,用非线性去冗算法实现模糊隶属度转换并建立凝汽器状态评价的非线性评价模型.     

用于太阳能光伏发电的高倍聚光系统

 研究了基于三结型（InGaP/InGaAs/Ge）高效太阳能电池的太阳能光伏发电的高倍聚光系统。该系统采用高次非球面光学玻璃卡塞格林系统,运用Zemax和Tracepro光学设计软件完成200~500倍太阳能聚光系统的设计,同时设计了单片型高倍太阳能聚能光学组件,用热压成型方法研制了太阳能聚能透镜（副镜）。采用16个性能相同的聚光光学组件和相同数量的三结型太阳能电池组成高倍聚光型太阳能光伏组件,极大地提高了聚光比,为太阳能光伏发电的高倍聚光器设计提供参考和依据。     

太阳模拟器中椭球面聚光镜参数的确定

椭球面聚光镜是太阳模拟器设备的重要组成部分,其能量收集的效率决定着太阳模拟系统的能量传递效率,而太阳模拟器光学系统中的椭球面聚光镜参数一直没有理论上的设计依据,结合氙灯的发光特性并通过对MATLAB 中建立的椭球面聚光镜聚光过程数值分析模型给出了椭球面聚光镜包括第一焦距、最大成像放大倍率、包容角范围及前后开口直径的确定依据,并通过在Lighttools 中建立的4种仿真模型验证了理论分析的正确性。第一焦距由光源光中心高确定,最大成像放大倍率由光学积分器相对孔径及椭球镜包容角范围共同确定,椭球镜包容角范围不小于30°～120°,前开直径口由椭球镜的最大孔径角确定,后开口直径由最小孔径角和光源的径向调节量共同确定。该结论给椭球面聚光镜的设计提供了理论支撑,有利于设计完成高能量收集效率的椭球面聚光镜。     

多层膜聚光镜对Schwarzschild显微镜成像均匀性的影响

提出了利用多层膜聚光镜提高Schwarzschild显微镜成像均匀性的方法。设计了聚光镜的光学结构,使80%的等离子体辐射能量会聚在约0.8 mm直径的范围内。根据成像系统的工作波长和光线在聚光镜表面的入射角度,设计了Mo/Si周期多层膜,制备了聚光镜光学元件,膜层周期厚度为9.64 nm,周期数为30,对18.2 nm波长的峰值反射率为51.7%。利用所设计的聚光镜作为照明系统,对Schwarzschild物镜进行了网格成像实验。结果表明:在1.2 mm视场内可以实现2.5 μm的空间分辨力,并且完全消除了物镜中心遮拦所造成的像面光强分布不均匀性。     

Development of a Solid-Phase Extraction Procedure for the Simultaneous Determination of Polyphenols, Organic Acids and Sugars in Wine

A solid-phase extraction (SPE) procedure that fractionates wine samples into 2 sub-samples containing sugars and organic acids (sub-sample 1) and low molecular weight polyphenols (sub-sample 2), respectively, together with rugged LC procedures for their analyses are described. Wine is adjusted to pH 2.5 and loaded on a styrene-divinylbenzene (SDB) cartridge. The organic acids and sugars are eluted with 20 mM sulphuric acid and the monomeric polyphenols with ethyl acetate. Glucose and fructose are analysed by normal phase LC with evaporative light scattering detection and the organic acids by ion exclusion chromatography with UV detection at 210 nm. Analysis of the phenolic fraction is performed by reversed phase LC with diode array detection. Recoveries and repeatabilitys for 27 standard compounds (2 sugars, 7 organic acids and 18 polyphenols) are presented. The method represents an improvement in terms of productivity and robustness compared to currently used procedures.     

Uncertainty in the determination of glucose in aqueous solutions by high‐performance liquid chromatography with evaporative light scattering detection

The determination of glucose and other carbohydrates is the most widespread chemical analysis that is performed within the industries of food, beverage, forage, biomass, pulp and paper, pharmaceuticals among others. Besides that, sugar refineries need to control their products, by‐products and effluents, and furthermore, glucose in the sucrose refining process, is considered an impurity, which shall be controlled. Being HPLC the most currently instrumental technique used for glucose analysis, the evaporative light scattering detector (ELSD) offers advantages (sensitivity, possibility for operating in gradient mode) over the also used refractive index detector. In this work, an HPLC‐ELSD methodology was optimised and validated, aiming the estimate of the uncertainty associated with the results at low levels of concentration of glucose to be measured. Linearity of the response was obtained in the range of glucose concentrations from 20 to 300 mg/L, with an analysis time of 10 min. The global uncertainty was estimated accordingly to the bottom‐up approach used by Eurachem. It was 13% on average for concentrations from 100 to 300 mg/L. For lower concentrations, uncertainty increased significantly up to 30% in the vicinity of the LOD of the method.     

硫化锰夹杂溶解和微生物存在对不锈钢管发生点蚀

结合发电厂凝汽器不锈钢管内壁腐蚀部位分布规律和腐蚀外貌特征,分别对腐蚀部位沉积物、内壁蚀孔附近管材成分进行扫描电子显微镜观察和能谱分析,探讨了管材中MnS溶解与微生物对凝汽器不锈钢管腐蚀的电化学反应机理,发现二者在点蚀形成过程中具有协同作用,并在综合分析影响不锈钢腐蚀的各种因素的基础上,提出了不锈钢凝汽器在运行过程中应采取的防护措施。     

微流蒸发光散射检测器的研制及评价

构建了适用于纳升级到微升级流量的毛细管分离体系的微流蒸发光散射检测器(μELSD),实现了其与毛细管液相色谱(eLC)的联用.对雾化器孔径和雾化毛细管内径、蒸发管内径和长度、光散射池尺寸、雾化毛细管位置和辅助载气流量等参数进行了优化.在最优条件下,微流蒸发光散射检测器检出限为直接进样葡萄糖1 ng(S/N＞ 10),线性范围0.01～1.0 μg,重复性好,峰面积RSD(n=6)为0.4％,峰高RSD(n=6)为0.3％.本检测器已成功应用cLC-μELSD平台,使用C18毛细管色谱柱(内径250 μm),0.1％甲酸铵溶液(pH 4.5)-甲醇(60∶40,V/V)为流动相,分离检测了3种常用甜味剂,表明本研究构建的系统可以应用于实际分离检测中,具有分析时间快、溶剂消耗量少、样品需求量小的优点.