Biomedical subjects

Zdena Malá

Publications and source records attributed to Zdena Malá.

5 recordsLinked to original sources

PubMed2007

Recent progress in capillary ITP.

ITP has been attracting constant attention for many years due to its principal capability to concentrate trace analytes by several orders of magnitude. In the current capillary format, it is able to concentrate trace analytes diluted to several microliters of an original sample into concentrated zones having volumes in the range of picoliters. Due to this reason, ITP holds an important position in many current multistage and multidimensional separation schemes. This article links up previous reviews on the topic and summarizes the progress of analytical capillary ITP since 2002. Almost 100 papers are reviewed that include methodological novelties, instrumental aspects, and analytical applications. Papers using ITP and/or isotachophoretic principles as part of multistage and/or multidimensional separation schemes are also included.

Chemistry, Pharmaceutical↗

PubMed2007

Contemporary sample stacking in CE: a sophisticated tool based on simple principles.

Sample stacking is a general term for methods in CE which are used for on-line concentration of diluted analytes. During the stacking process, analytes present at low concentrations in a long injected sample zone are concentrated into a short zone (stack). The stacked analytes are then separated and individual zones are detected. Thus stacking provides better separation efficiency and detection sensitivity. Many papers have been published on stacking till now, various procedures have been described, and, many names have been proposed for stacking procedures utilizing the same principles. This contribution brings an easy and unified view on stacking, describes the basic principles utilized, makes a list of recognized operational principles and brings an overview of principal current procedures. Further, it surveys selected recent practical applications ordered according to their operational principles and includes the terms, nicknames, and acronyms used for these actual stacking procedures. This contribution may help both newcomers and experts in the field of CE to orient themselves in the already quite complex topic of sample stacking.

Electrophoresis, Capillary↗

PubMed2006

A new type of migrating zone boundary in electrophoresis: 2. Transient sample zone shapes.

A new type of migrating zone boundary in electrophoresis is presented theoretically and evidenced experimentally. This type of the boundary (called hybrid boundary) shows simultaneously a steady-state part with self-sharpening properties and an unsteady-state part with time-dependent electromigration dispersion. It is shown that a sample zone may possess a hybrid boundary both as its front and rear one simultaneously. In such a case, the evolution of a sample zone injected originally as a rectangular pulse exhibits very complex transient shapes before it reaches the well-known fronting or tailing triangular shape. Depending on the stage at which detection of such a sample zone occurs, variable and peculiar-shape peaks may appear in the electropherogram. Based on theoretical predictions, experimental examples of the above-mentioned phenomena are presented in this contribution for direct and indirect UV absorbance detection of sample zones. Excellent agreement of theoretical predictions with the experiments has been found. The knowledge of hybrid boundaries is of key significance for correct interpretation of records of CE analyses in practice.

Electrophoresis↗

PubMed2006

A new type of migrating zone boundary in electrophoresis: 3. The hybrid boundary and stacking criteria.

This article investigates the principles of stacking of analytes by a zone of a bulk sample component that possesses one hybrid boundary. The model system investigated comprises a transient stacking zone in a BGE where the rear boundary of this zone is a hybrid one. A theoretical description of such a system is given, and general rules and mathematical criteria for quantitative stacking are presented. These criteria are based on comparison of migration velocities of analytes to be stacked and velocities of the boundaries of the stacking zone. It is shown that the presence of a hybrid boundary brings about additional constraints for stacking of analytes due to the presence of the sharp part of the hybrid boundary that migrates faster than regular sharp boundary of this zone. An experimental example related to the described theory is also shown.

Computer Simulation↗

PubMed2006

Properties of moving boundaries in electrophoretic systems with multivalent weak electrolytes: principles of non-Kohlrausch concentration adjustment.

This paper describes the properties of electrophoretic moving boundaries in systems containing multivalent weak electrolytes where the Kohlrausch regulating law is not valid. It is shown that zones of unexpected properties can be formed in such systems and that the adjusted concentrations in these zones cannot be predicted using present knowledge. A theoretical approach to the properties of such "non-Kohlrausch" systems is presented that allows the explanation and prediction of their properties. The theory based on velocity diagrams describes the electrophoretic evolution of a concentration boundary between a pair of zones (differing only in the concentration ratio of their components) as the formation of two moving boundaries migrating in opposite directions. The concentration profiles and velocities of these moving boundaries, that can be either sharp or broadening by electromigration dispersion, as well as the adjusted concentrations in the formed intermediate zones can be predicted from calculated velocity diagrams. Such zones differ from normal systems in that their adjusted concentrations are a function of the composition of both zones that formed the original boundary. The theory is illustrated and verified by both computer simulations and experiments.

Computer Simulation↗