Hydrophilic interaction liquid chromatography--mass spectrometry for the analysis of paralytic shellfish poisoning (PSP) toxins

Hydrophilic interaction liquid chromatography (HILIC) was examined for the separation of paralytic shellfish poisoning (PSP) toxins using the stationary phase TSK-gel Amide-80. The parameters tested included type of organic modifier and percentage in the mobile phase, buffer concentration, pH, flow rate and column temperature. Using mass spectrometric (MS) detection, the HILIC column allowed the determination of all the major PSP toxins in one 30 min analysis with a high degree of selectivity and sensitivity. The high percentage of organic modifier in the mobile phase and the omission of ion pairing reagents, both favored in HILIC, provided limits of detection (LOD) in the range 50-100 nM in selected ion monitoring (SIM) mode on a single quadrupole LC-MS system. LOD in selected reaction monitoring (SRM) mode on a sensitive triple quadrupole system were as low as 5-30 nM. Excellent linearity of response was observed.     

The assessment of electronic balances for accuracy of mass measurements in the analytical laboratory

The accuracy of mass measurements when using electronic balances is considered within the frame of analytical assays in terms of the uncertainty budget according to the internal quality control routine, the calibration process, the balance specifications, and the weighing scenarios. Buoyancy corrections for both conventional and true mass are fully discussed. The procedure is illustrated with a worked example.     

材料组成特性的统计表征--原位统计分布分析

提出了原位统计分布分析的新概念，它以测试信息原位性、原始性、统计性为特征，旨在反映材料中较大尺度（cm^2）范围内不同组成的定量统计分布规律，系现有宏观平均含量分析及微观结构分析之外的另一种材料性能表征的技术。以火花光谱无预燃单次放电（SDA）、连续激发及高速采集解析技术为基础，研制了金属材料原位分析仪。火花光谱单次放电（SDA）研究指出，在无预燃的情况下，每一个火花单次放电的信号都与该材料对应位置及原始状态相关。当对材料在较大尺度范围内，实现无预燃激发时，则可以获得几万个、几十万、乃至几百万个单次放电的信号，它们分别与各自放电的原始位置厦原始状态相对应。在信号统计解析的基础上，提出了一些表征材料性状的新信息，如在材料中，各元素不同位置含量的统计定量分布；各元素偏析度的准确定量计算；元素不同含量在材料中所占的原位（置）权重比率（统计偏析度）；统计致密度；夹杂物及粒度的统计定量分布等．该技术成功地应用于连铸等冶金工艺、材料研究及生产的质量判据。     

Sequence Analysis of Polypeptide by Mass Spectrometry

The method described in this work provides a sensitive and fast technique for investigating the primary structure of peptides with molecular weight up to 3340 amu. Usually, the metastable ion kinetic energy spectra (MIKES) and collisional activated decomposition (CAD) spectra provide complementary information for the FAB mass spectra, the MIKES and CAD spectra generally contain high-mass sequence ions.     

红外光谱计算分析鉴别海面溢油源的研究

本法将数字化的溢油和可疑溢油源样品的红外光谱视为N—维空间的两个矢量,它们间的角距离即作为定量比较两油品相似程度的依据。计算时选用表征油品组成特征的四个关键谱带:1600、1375、810和720cm~(-1)作为分析谱带。为了降低实验误差和风化影响,附加了一种新的数学处理过程,研究规划出N行M列(N>M)的线性矛盾方程组,用最小二乘解法处理原始数据求得问题的最可信赖解,从而用计算分析取得令人满意结果,并在现场执法服务中得到证实。     

Immobilized pH gradients as a first dimension in shotgun proteomics and analysis of the accuracy of pI predictability of peptides

In this work, we demonstrate the potential use of immobilized pH gradient isoelectric focusing as a first dimension in shotgun proteomics. The high resolving power and resulting reduction in matrix ionization effects due to analyzing peptides with almost the exact same physiochemical properties, represents a significant improvement in performance over traditional strong cation-exchange first-dimensional analysis associated with the shotgun proteomics approach. For example, using this technology, we were able to identify more than 6000 peptides and > 1200 proteins from the cytosolic fraction of Escherichia coli from approximately 10 microg of material analyzed in the second-dimensional liquid chromatography-tandem mass spectrometry experiment. Sample loads on the order of 1 mg can be resolved to 0.25 isoelectric point (pI) units, which make it possible to analyze organisms with significantly larger genomes/proteomes. Accurate pI prediction can then be employed using currently available algorithms to very effectively filter data for peptide/protein identification, and thus lowering the false-positive rate for cross-correlation-based peptide identification algorithms. By simplifying the protein mixture problem to tryptic peptides, the effect of specific amino acids on pI prediction can be evaluated as a function of their position in the peptide chain.     

四苯基卟啉金属螯合物的反相高效液相色谱保留行为研究

 研究了四苯基卟啉金属螯合物(TPP)的高效液相色谱保留行为。在C18柱上试验以各种有机溶剂洗脱金属螯合物,最终选择了甲醇-丙酮的非 水体系作流动相。各螯合物的保留顺序为：ZnTPP＜TPP＜NiTPP＜CuTPP。运用Horvath的疏溶剂理论解释了这种保留行为。文中采用电负性与离子半径之比（EN／ri）作为静电场强的量度,提出 EN／ri值作为四苯基卟啉金属螯合物保留值参数。实验发现,在不同的流动相配比条件下,lnk′与 EN／ri均呈良好的线性关系。     

Stochastic scheduling problems II-set strategies-

The paper introduces the finite class of set strategies for stochastic scheduling problems. It is shown that the knownstable classes of strategies such as ES and MES strategies are of this type, as arelist-scheduling strategies such as LEPT and SEPT and other, more complicatedpriority-type strategies. Roughly speaking, set strategies are characterized by the fact that the decision as to which jobs should be started at timet depends only on the knowledge of the two sets of jobs finished up to timet and being processed at timet. Contrary to list scheduling strategies, set strategies may involve deliberate idleness of machines, i.e. may not be greedy and can therefore not generally be induced by priority rules. It is demonstrated that set strategies have useful properties. They are e.g. ⁿ -almost everywhere continuous and therefore show satisfactorystability behaviour w.r.t. weak convergence of the joint distribution of job durations. Furthermore, the optimum w.r.t.all strategies is already attained on this class if job durations are independent and exponentially distributed and the performance measure fulfills a certainshift condition. This shift property is a quite natural concept and generalizes aspects of the notion ofadditivity in semi-Markov decision theory and stochastic dynamic optimization. Its complete analytical characterization is a major object of this paper. Typical additive cost criteria such as makespan and flowtime are of course covered, which yields simultaneously a first step towards generalization of optimality of LEPT and SEPT rules, as known for special cases. In fact, in view of the obtained optimality result, the question of when deliberate idleness of machines can be avoided, gains considerable interest, as it characterizes stochastic environments in whichpriority strategies are optimal. This provides a major link with current research on the analysis of networks of queues in the context of computer systems.The work of the first two authors was supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen, while the work of the last author was supported by DAAD.     

饮用水中辛硫磷降解及代谢物的气相色谱／质谱定性分析研究

本文采用GDX-102和GDX-501混合树脂富集和气相色谱/质谱联用分离定性的方法。测定了受农药厂排出废水污染的深层地下水中的有机污染物。从样品中检出了三种硫代磷酸酯类化合物.经分析为该农药厂辛硫磷农药生产过程中的降解物和代谢物。