Informationsgehalt der quantitativen Analyse

Ohne Zusammenfassung     

Immunoextraction of zinc proteins from human plasma using chicken yolk antibodies immobilized onto paramagnetic particles and their electrophoretic analysis

Zinc(II) as the only transition metal lacking redox activity is an essential part of approximately 10% proteins as a cofactor of these proteins. Considering the fact that there are numerous zinc(II) containing proteins, proteomics and metallomics studies aimed on them require accurate methods for preparation of real biological samples prior to their subsequent analysis using 2DE and MS. For this purpose, we suggested a new method based on chicken anti-zinc antibodies and magnetizable particles. Antibodies were covalently immobilized to the surface of paramagnetic beads activated with tosyl group. Binding of the antibody to the beads was confirmed by secondary anti-chicken antibody conjugated with horseradish peroxidase. The immunoextraction conditions, such as concentration of the beads (6-18 μg/mL of the sample), time of immunoextraction (6-34 min), pH and composition of the elution buffer, and time of extraction (48-300 s) were optimized. Subsequently, zinc proteins were extracted from human plasma and total concentration of zinc was monitored by electrochemical detection in the extracts. Under optimal conditions it was possible to monitor the proteins and zinc removal from the sample by chip CE, SDS-PAGE, and indirectly using electrochemistry.     

Atom probe study on the segregation behavior of the binary alloy Pt95Mo5

Atom-probe measurements have been carried out to study the segregation behavior of the binary alloy Pt95Mo5. On in situ annealed specimens a significant surface enrichment of molybdenum has been observed. Prolonged heat treatment results in a final Mo concentration of about 30 at.% extended about 2 nm into depth. This surface layer can be interpreted as the intermediate phase Pt₂Mo. The experimental result can be satisfactorily explained with the quasichemical model of Guggenheim.     

Effects of redox conditions and zinc(II) ions on metallothionein aggregation revealed by chip capillary electrophoresis

Metallothioneins (MTs) belong to cysteine-rich proteins with unique higher structure. One of the most known MT's functions is metals detoxification and maintaining their homeostasis in a cell. Structure of MT with naturally occurred zinc(II) ions can be affected by concentration of metal ions as well as redox milieu inside a cell, however the exact explanation and biochemical effects of the structural changes are still missing. In this study we used capillary electrophoresis on chip coupled with fluorescence detection to determine structural changes of MT with increasing concentration of zinc(II) ions and under various redox conditions. To investigate the structural-dependent effects, reduced and/or oxidized apo-MT (MT without natural occurred metal ion) was prepared. Zinc binding into reduced and/or oxidized apo-MT was compared. MT was incubated with 0, 5, 15, 25, 50 and 100 μM ZnCl₂ for 1 h in 37 °C. Formation of MT aggregates with increasing zinc concentration was observed by spectrophotometry, chip capillary electrophoresis, and SDS-PAGE. We found out that reduced MT forms aggregates more readily compared to oxidized MT. Using the chip capillary electrophoresis allowed us relative quantification of MT aggregation as a decrease in the area of the signal corresponding to the monomer form of MT (Mw 15 kDa, migration time 26.5 s) and its ratio to total signal (sum of all signals measured by the electrophoresis). The dependences had an exponential character with equation y = 2.4 × e^−0.01x, R² = 0.945 for 15 kDa peak area and y = 0.11 × e^−0.01x, R² = 0.938 for decrease of 15 kDa peak area ratio to the total signal. Zn–MT interaction was 30% faster during the first 15 min and 50% faster during the whole experiment for reduced MT. It can be concluded that formation of MT aggregates is dependent on redox state and Zn(II) concentration.     

Information efficiency of analytical methods

The concepts of information efficiency and profitability are discussed in relation to analysis.     

Doxorubicin Encapsulation Investigated by Capillary Electrophoresis with Laser-Induced Fluorescence Detection

Doxorubicin (DOX) belongs to the group of anthracycline antibiotics with very effective anticancer properties. On the other hand, the cardiotoxic effects limit its application over the maximum cumulative dose. To overcome this obstacle, encapsulation of this drug into the protective nanotransporter such as apoferritin is beneficial. In this study, fluorescent behavior of DOX in various solvents was determined by fluorescence spectrometry, demonstrating the fluorescence quenching effect of water, which is often used as a solvent. It was found that by increasing the amount of the organic phase in the DOX solvent the dynamic quenching is significantly suppressed. Ethanol, acetonitrile and dimethyl sulfoxide were tested and the best linearity of the calibration curve was obtained when above 50 % of the solvent was present in the binary mixture with water. Moreover, pH influence on the DOX fluorescence was also observed within the range of 4–10. Two times higher fluorescence intensity was observed at pH 4 compared to pH 10. Further, the DOX behavior in capillary electrophoresis (CE) was investigated. Electrophoretic mobilities (CE) in various pH of the background electrolyte were determined within the range from 16.3 to −13.3 × 10 ⁻⁹ m⁻² V⁻¹ s⁻¹. Finally, CE was also used to monitor the encapsulation of DOX into the cavity of apoferritin as well as the pH-triggered release.

     

Informationstheorie in der Analytik

Zusammenfassung Ausgehend von der Systematik analytischer Informationen und vom analytischen Prozeß als Informationsverarbeitungsprozeß wird ein Überblick gegeben über die informationstheoretischen Grundlagen der Analytik. Die Ermittlung des Informationsgehaltes von Analysenverfahren und -ergebnissen für qualitative und quantitative Einkomponentenanalysen wird unter Berücksichtigung realer analytischer Bedingungen abgeleitet und der Einfluß des Erwartungsbereiches, der Genauigkeit und Richtigkeit von Analysenergebnissen untersucht. Probleme der Kalibrierung quantitativer Analysenverfahren und der Zusammenhang zwischen Nachweisvermögen und Informationsgehalt von Spurenanalysen werden betrachtet.

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Information theory in analytical chemistryI. Principles and application to single-component analyses

Summary Starting from the system of analytical informations and from the analytical process as information processing technique a review is given about the information-theoretical fundamentals of analytical chemistry. The determination of information contents of analytical procedures and results in the cases of qualitative and quantitative single-component analyses is derived under the assumption of really existing analytical conditions. The influence of such properties as expectation range, precision and accuracy is discussed. Furthermore, the problems of calibration of quantitative analytical procedures and the relation between information content and detection limit in trace analysis are considered.

     

Optimization of information properties of NAA with respect to information content and profitability of results

Information properties of analytical results together with other important parameters especially economic ones can be used for the optimization of analytical procedures. Therefore, we have proposed a computational technique for the optimization of multielement neutron activation analysis (NAA) based on the information content and profitability. The optimization starts with the prediction of the -ray spectra to be expected during analysis under given experimental conditions (sample size, irradiation, decay and counting times etc.) and with the calculation of detection and determination limits. In the next step, the information contents for the determination of particular elements and for the simultaneous determination of element groups are computed. The information content depends or is closely connected with such properties of the method as selectivity, sensitivity, precision, accuracy and, as in the other cases of trace analysis, also with the detection limit. Then, the information profitability (IP) taking into account the information content and relevance (appreciation of specific information according to its contribution to the solution of a given problem) together with economic aspects can be calculated. This function can be used for the optimization of a particular NAA procedure, for the mutual comparison of different variants of NAA and also for the comparison with other analytical methods. The use of information profitability for the optimization of NAA is shown on a practical example of the INAA analysis of urban particulate matter SRM 1648 produced by NBS (USA).