Improved quantification limits in chiral capillary electrochromatography by peak compression effects

The peak compression effect has been applied to improve quantification limits in chiral capillary electrochromatography (CEC). A stationary phase based on the chiral selector vancomycin (Chirobiotic V) was used for separations of the enantiomers of mianserin. By adding solvents with a low dielectric constant, e.g. 2-propanol or tetrahydrofuran, to the sample solution, peak compression could be induced. The plate numbers for the minor enantiomer increased from approximately 100,000 to 1.4-1.6 million plates/m, when the composition of the mobile phase was adjusted so that the analyte eluted within either one of two system zones originating from the sample solution. A 10-fold improvement in the quantification limit for the minor enantiomer was obtained compared to elution under non-focused conditions.     

ICP－MS用于Eu_2O_3标准物质中铝和锌的定值分析

报道了用电感耦合等离子体质谱法测定氧比铕标准物质中Ａｌ_２Ｏ_３和ＺｎＯ的方法。考察了谱干扰和基体影响，采用Ｒｈ为内标较好地补偿了基体铕的影响。方法简便、快速，定值准确、可靠。     

氢化物发生-原子荧光光谱法测定水中汞的测量不确定度分析

对氢化物发生-原子荧光光谱法测定水中汞的分析方法的测量不确定度进行了估计。认为在分析的全过程中,标准溶液的配制、校准曲线的绘制以及试样的分析是测量不确定度的三项主要来源。基于这一认识,建立了相应的数学模型,对关系式中的各个变量作了分析并对其不确定度进行量化。最后,按统计学的计算方法给出了合成不确定度和扩展不确定度。     

Optical biosensor for pharmaceuticals, antibiotics, hormones, endocrine disrupting chemicals and pesticides in water: Assay optimization process for estrone as example

Certain contaminants at trace concentrations in surface waters can have dramatic effects on the hormonal system of organisms in the aquatic environment. Therefore, immunoanalytical methods at a very low limit of detection (LOD) and a low limit of quantification (LOQ) are becoming more and more important for environmental analysis and especially for monitoring drinking water quality. Environmental monitoring of antibiotics, hormones, endocrine disrupting chemicals, and pesticides in real water samples (e.g. surface, ground or drinking water) with difficult matrices places high demands on chemical analysis. Biosensors have suitable characteristics such as efficiency in allowing very fast, sensitive, and cost-effective detection. Here we describe an assay optimization process with a fully automated immunoassay for estrone which resulted in a LOD below 0.20 ng L⁻¹ and a LOQ below 1.40 ng L⁻¹. In contrast to common analytical methods such as GC-MS or HPLC-MS, the biosensor used requires no sample pre-treatment and pre-concentration. The very low validation parameters for estrone are the result of the continuous optimization of the immunoassay. The basis of our sensitive assay is the antibody with a high affinity constant towards estrone. During the optimization process, we reduced the amount of antibody per sample and improved the chip surface modification. Finally, this proceeding led to a calibration routine with an amount of antibody of only 3.0 ng per sample (sample volume: 1.0 mL). The reduction of the amount of antibody per sample results in better validation parameters (LOD, LOQ, and IC₅₀), but this reduction leads to the current device-related limitation of the River Analyser (RIANA).For some endocrine disrupting compounds, no effect levels (NOELs) in the lower nanogram per liter range are reported. This defines the challenge, which analytical methods have to compete with and our RIANA instrument with its improved sensitivity for the detection of a single hormone in the lower nanogram per liter range is a powerful tool in aquatic analytics in addition to the common analytical methods.     

磺酰脲类除草剂的三维药效团模型

磺酰脲类除草剂是七十年代末期[1，2]开发的一类超高效除草剂，杀草谱广，用量极低．它通过抑制植物体内乙酰乳酸合成酶（ALS，acetolactatesynthase）的活性[3]，破坏支链氨基酸缬氨酸、亮氨酸和异亮氨酸的合成，造成杂草的死亡．本文从三维角度出发，利用先进的三维分子设计软件APEX（ActivityPredictionExpertSystem）－3D[4]，建立破酸豚类除草剂药效团模型（biophoremodel），辅助设计、筛选活性化合物；再由药效团构造出模拟ALS酶活性位点（activesites）的空间结构，以该模拟结构为基点，以期设计出全新结构的ALS酶抑制剂的…     

光敏聚合中含二苯酮基高聚物的引发作用

合成了多种不同分子量和不同二苯酮侧基含量的高分子敏化剂PVB,从紫外吸收光谱及发射光谱的测定结果表明,PVB基本保持小分子二苯酮(BP)的光化学特性。采用PVB与叔胺组成光敏引发体系引发MMA光聚合时,聚合速度(R_ο)与小分子相比增加二倍以上。而且R_p随PVB分子中二苯酮基含量的增加而增加,当PVB分子量提高时引发聚合能力加强,这和高分子敏化剂分子链中高效率的能量传递以及色基的密集分布特性有关。     

封闭压力酸溶-ICP-MS法分析地质样品中47个元素的评价

对封闭压力酸溶－ICP－MS法同时测定地质样品中47个元素的效果和适用范围进行了实测评价。并对溶样条件进行了优化。实验结果表明，HF－HNO3高温高压酸溶是一种有效的样品分解方法，在所测定的47个元素中，大部分元素如Li,Be,Ti,V,Mn,Co,Ni,Cu,Zn,As,Zr,Nb,Mo,Cd,In,Sn,Sb,Hf,Ta,W,Tl,Pb,Bi等在大多数标样中在三种取样量下都可以得到满意的回收率。而Sc,Cr,Ga,Y,REE,Rb,Cs,Sr,Ba,Th,U等元素在大部分样品中则随取样量减少，回收率上升，在一些样品中，当取样量降至25mg时，可以获得满意的回收率。用王水代替HNO3复溶残渣，利用氯离子的络合作用促进复溶，使许多元素的回收率有了明显的提高。     

Nanostructure evolution studies of bulk polymer materials with synchrotron radiation: progress in method development

The prospects of a modern analysis of nanostructure evolution during the processing of polymer materials by means of scattering from synchrotron radiation are demonstrated in examples. The beam sources have gained stability, shortages are located in beamline setups and in method development for the quantitative analysis of voluminous data sets.By using the proposed multidimensional chord distribution function (CDF) analysis method, nanostructure information from small-angle X-ray scattering (SAXS) data are extracted and visualised. The method can be automated if the beamline setup is able to deliver a full data set with simple constraints. In this case even a simultaneous data evaluation is possible (while one pattern is accumulated, the previous one is analysed). The advantages of the method are demonstrated in a study of the straining of a thermoplastic elastomer. The possibilities of an automated analysis are demonstrated in an investigation of the crystallisation behaviour of high-pressure injection-moulded polyethylene (HPIM-PE). The achievable results of nanostructure analysis of polymer materials are discussed. It is shown that the time-resolved SAXS of polymer materials studied during a transformation and analysed by the CDF method is not just a powerful tool to investigate the relationship between structure and properties of materials; the information that can be gained concerning the processes that control nanostructure evolution is equally important. In the future the enlightenment of such relationships may help to tailor polymer materials with respect to their properties and, beyond that, to improve assessments concerning their aging.     

The construction and evaluation of a high pressure manifold and vessels for a Calvet type microcalorimeter

A Setaram C-80 calorimeter has been modified in order to measure the heat flow of energetic materials at pressures up to 69 MPa. A manifold and sample cells capable of operating at high pressure were designed, constructed and evaluated. This paper will describe, in detail, the high pressure manifold construction, safety assessment and calibration. As well, the results for initial trials with ammonium nitrate (AN), and pentaerythritol tetranitrate (PETN) at various pressures and heating rates will be discussed.     

具有偏差变元的双曲型微分方程组解的振动性

本文获得了双曲型方程组在齐次Neumann,Dirichlet和Robin边值条件下,所有解振动的充分条件.