Characterization of the chemical homogeneity of solid-state standard materials by chemometric methods

Summary For characterizing the homogeneity of a copper standard for optical emission spectrometry, the results of spark source mass spectrographic (SSMS) milliprobing have been treated by diverse chemometric methods. The proposed strategy includes visualization of the data, global homogeneity testing for each element, testing the anisotropy of elemental distributions, search for correlation between elements, and statements on the homogeneity with respect to other analytical procedures. The copper standard was proved to be non-homogeneous for SSMS but homogeneous for techniques of optical emission spectroscopy having larger sampling volumes.

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Homogenitätscharakterisierung fester Standardproben unter Verwendung chemometrischer Methoden

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Total serum protein N-glycome profiling on a capillary electrophoresis-microfluidics platform

We implemented 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled asparagine-linked glycan (N-glycan) profiling on a microfluidic electrophoresis platform. Using 11.5 cm effective length etched channels and 4% linear polyacrylamide as the separation matrix, the major N-glycans in human serum were profiled in 12 min with a resolution comparable to what is achieved for these analytes on gel-based DNA sequencers. This demonstration suggests a practical clinical application for high-speed compact analyzers which might be uniquely based on microfluidic devices.     

Die Einwirkung von Schwefelnatrium auf freies, festes Jod und Jod in w?sseriger L?sung und Anwendung dieser Reaktion in der Analyse

Ohne Zusammenfassung     

Plasma jets produced by low energy laser pulse interaction with planar and cratered targets

Laser experiments of the plasma jet formation using nanosecond laser pulses with low energy, i.e., <20 J, are presented. Planar and cratered gadolinium and aluminum targets are irradiated with laser intensities of several 10¹⁴ W/cm². Spatially-resolved time-integrated X-ray spectra were recorded in the spectral range from 7 to 10 Å. A jet-like structure is obtained from aluminum targets with a preformed crater, which is not seen in planar target irradiation. For gadolinium, a jet is observed from both planar and preformed cratered targets, suggesting that the collimation is dominated by radiative cooling. A radiation-hydrodynamics code coupled to a non-LTE ionization code was used to model the plasma. The calculated plasma emission was found to be consistent with the experimental results.     

Characterization of the antioxidative activity of novel nontoxic neuropeptides by using capillary electrophoresis

In the present study, we have monitored the oxidation process of novel nontoxic neuropeptides and determined its rate constants, which describe the antioxidative potential of the peptides. A capillary electrophoretic method was implemented which ensures the simultaneity of analysis of reactants and products in a short time of analysis. The rate constants of oxidation of the four novel peptides, 4-methoxy-L-tyrosinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF1), D-serinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF6), 4-methoxy-L-tyrosinyl-alpha-L-glutamyl-L-cysteinyl-glycine and D-serinyl-alpha-L-glutamyl-L-cysteinyl-glycine, designed by us, were compared with those of oxidation of glutathione (reduced glutathione) by using capillary electrophoresis. The second-order rate constants were similar for all peptides if the oxidation was carried out with hydrogen peroxide (k(II) = 0.208 - 0.236 x 10(3)/M.min). The rate constants were also determined for the mixtures of peptides. When the oxidation is caused by hydroxyl radical (OH*), the gamma-glutamate containing peptides (UPF1 and UPF6) exhibited two to four times higher antioxidative activity (k(II) = 4.428 and 2.152 x 10(3)/M.min, respectively). The results suggest that the antioxidative potential of the peptides studied is not determined by the formation of disulphide bridge alone.     

Trends in Sorption Recovery of Platinum Metals: A Critical Survey

The major trends in research into the sorption recovery and separation of platinum metals are critically surveyed. The advantages and disadvantages are described for ion-exchange and complexing sorbents based on organic polymers, chemically modified silicas, sorbents with applied macrocyclic compounds, hybrid organomineral sorbents with supported polymers, molecular imprinted sorbents, solid-phase extractants based on ionic liquids, biosorbents, and other types of sorbents. The technological potentials of these sorbents are evaluated.     

Electron spin resonance in polyphenylacetylene

By polymerizing phenylacetylene in the absence of initiator and in vacuo while observing electron spin resonance, it was established that the paramagnetism in the thermal polymer (PPA-T) cannot be due to interaction with oxygen but must be a property of the chemically uncontaminated macromolecule. The ESR behavior of a concentrated solution of PPA(T) in monomer and of solid (amorphous) PPA(T) displays a Curie dependence, whereas the ESR absorption of crystalline polymer made with coordination catalysts increases by one to two orders of magnitude over the temperature of about 60 to 140°C. The major portion of the XRD crystallinity disappears more sharply, at about 120°C. The paramagnetism in PPA must therefore be associated with “conformational defects” in the individual macromolecules.