CZE-ICP-MS separation of metallothioneins in human brain cytosols: comparability of electropherograms obtained from different sample matrices

Capillary zone electrophoresis, with its high resolution capability in the separation of different compounds, is well suited for the investigation of metal-containing proteins, especially when elemental detection is conducted using hyphenated inductively coupled plasma-mass spectrometry. A major problem in the separation of proteins in body fluids is caused by the effects of different sample matrix composition. The migration time of proteins varies significantly, depending on the nature of the matrix. Electropherograms are consequently difficult to compare and the peak identification is uncertain. Pre-analytical steps for the reduction of matrix compounds enhance the quality of the data, but the results are still unsatisfactory. This paper describes a technique for obtaining electropherograms that can be used for comparison purposes by correction of the data with the aid of time markers. A mixture of five substances (caesium chloride, arsenocholine, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid) was added in a separate injection step. Ionic caesium eluted at the start of the separation and the other four markers appeared throughout and at the end of the electropherogram. All electropherograms were normalized to a reference run by recalculation of the time axis using the time markers. The method was applied to the analysis of human brain cytosols. Samples were separated after different pre-treatment steps and were compared, with special emphasis on the detection of the isoform metallothionein-3.     

Determination of trace elements in the water cycle by total-reflection x-ray fluorescence spectrometry

The determination of trace elements in the various stages of the water cycle is very important. Economic procedures for multi-element determinations of trace elements in various matrices are needed. The applications of total-reflection x-ray fluorescence spectrometry in this general area are reviewed briefly, with examples relating to rain, river and sea waters, sediments, particulate matter and manganese nodules and crusts, as well as mussel tissue. Up to 25 elements can be determined; these are S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Pb, Se, Rb, Sr, Y, Zr, Mo, Ag, Cd, Sb and Ba. Preliminary treatments of the various matrices are described. Accuracy checks by analysis of reference standards and by application of independent techniques are reported.     

Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Mitgeführte Biegelinie beim Hochgeschwindigkeitszug “ICE” — Teil II: Vergleich zwischen theoretischen und experimentellen Ergebnissen

Übersicht Im Teil I [1] der vorliegenden Arbeit wurden die theoretischen Ergebnisse der mitgeführten Biegelinie am Gleisoberbau (Schwellen/Schotter) bei der Überfahrt einer Achse des führenden, Drehgestells des ICE dargestellt. In diesem Teil II der Arbeit wird ein Vergleich der aus dem Teil I [1] erzielten theoretischen Ergebnisse mit Versuchungsergebnissen direkt am Gleisoberbau bei der Überfahrt des ICE durchgeführt. Außerdem wird die zusätzliche Leistung angegeben, die aufgrund der auftretenden Doppler-Effekte aufgebracht werden muß, um eine vorgegebene Fahrgeschwindigkeit einzuhalten.

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Live deflection line of the railway track caused by the high speed train ICE — Part II: Comparison between theoretical and experimental results

Summary In part I [1] of the work presented the theoretical results of the live deflection line of the conventional railway track caused by the travel of one single axle of the ICE's (Intercity Express) leading bogie are presented. In part II of the paper a comparison between the theoretical results obtained from part I [1] with experimental results from data measured on a railway track during the passage of the ICE train is given. In addition, due to Doppler effects apearing at the railway track, the additional portion of the ICE power required to keep the train's travelling velocity constant is also calculated in this paper.

     

Simultaneous determination of arsenic, selenium and antimony species using HPLC/ICP-MS

A new method for the simultaneous separation and determination of four arsenic species [As(III), As(V), monomethylarsonic acid and dimethylarsinic acid], three selenium species [Se(IV), Se(VI) and selenomethionine] as well as Sb(III) and Sb(V) is presented. The speciation was achieved by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Chromatographic parameters such as the composition and pH of the mobile phase were optimised. Limits of detection are below 4.5 μg L^–1 (as element) for Sb(III) and the selenium species and below 0.5 μg L^–1 for the other species. Precisions of retention times were better than 2% RSD and of peak areas better than 8% RSD for all the species investigated. Received: 13 January 1999 / Accepted: 4 March 1999     

Ein neues graphisches auswerteverfahren zur ermittlung stöchiometrischer faktoren gelöster komplexe

A computerized plotting method for the determination of the stoichiometry of complexes is introduced. The method has no assumptions or simplifications, and is applicable to both strong and weak complexes. Different stoichiometries, as a function of the metal to ligand concentration-ratio, can be identified in a single diagram. Furthermore, non-stoichiometric complexes can be recognized.