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Biomedical subjects

M Deml

Publications and source records attributed to M Deml.

12 recordsLinked to original sources
PubMed1994

Electrically controlled focusing of proteins and ampholytes between two modified electrolytes. Computer simulation.

Properties of the focusing in simple electrolyte systems using four-pole electrophoretic capillary column was evaluated by a computer simulation. Simulated concentration, pH and conductivity profiles confirm the previous experimentally observed features of the technique, i.e., high concentration capabilities, separation of the ampholytes and proteins into individual adjacent zones, sharp profile of zones and presence of only background electrolyte in the zone. Moreover, the influence of the magnitude of the solvolytic fluxes on the position of the zones in the column is demonstrated.

Buffers↗
PubMed1991

Electrophoresis with intermittent scanning of the migration path: detection of resolution within shortened time.

Intermittent optical scanning (by detection of optical density or fluorescence) of the electrophoretic migration path was applied to the resolution of two dyes under an arbitrary set of conditions. Scanning at 5-min intervals allows for detection of resolution between the two zones at least 3 times faster than conventional automatic zone detection employing a detector at the end of the migration path. This result promises that replacing stationary by mobile detectors in general would result in a substantial time saving for automated detection of electrophoretic zones.

Densitometry↗
PubMed1991

Electrophoretic size separation of particles with diameters in the micron range, using polymer solutions.

Polystyrene-sulfate particles ranging in size from 536 to 2,170 nm diameter were subjected to electrophoresis (10 V cm-1, 25 degrees C) in K-MES, 0.03 M ionic strength, pH 6.12, 50 mM CHAPS in liquid polymer media contained in horizontal glass tubes of 1 mm ID. The polymer media were linear polyacrylamide [0.3 to 0.9% Mr = 5 x 10(5) and 5 x 10(6), as well as a commercial solution of the latter in 4 M urea, 7.5% Na2SO4 designated as Gelamide-250] or polyvinylalcohol (0.25 to 2.5%, Mr = 6.5 x 10(5), designated PVA). In these polymer solutions, the polystyrene sulfate particles exhibit linear Ferguson plots [log(mobility) vs polymer concentration]. Their slope, KR, is directly related to the diameter of the particle when electrophoresis is conducted in Gelamide-250 or slowly 25 degrees C solubilized PVA solutions, indicating a molecular sieving mechanism. By contrast, KR is inversely related to the particle diameter when electrophoresis is conducted in linear polyacrylamide of 5 x 10(6) molecular weight or in PVA rapidly solubilized by autoclaving (121 degrees C, 1.2 kg cm-2 pressure), suggesting a particle exclusion (gel permeation) mechanism of size separation. Electrophoresis in solutions of polyacrylamide of 5 x 10(5) molecular weight exhibits the same degree of retardation for the entire size range of polystyrene particles used, i.e. a viscosity effect only and no size separation. Retardation of electrophoretic migration by either a sieving or a permeation mechanism is highly reproducible in polyacrylamide solutions, but not in PVA solutions (whether solubilization conditions favoring an apparent permeation mechanism or a sieving mechanism are applied).(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗
PubMed1990

Mathematical description of electrophoretic separation of weak acids by means of an H+ pulse.

The paper gives a detailed theoretical description of the recently published principle of separation by a dynamic pulse in zone electrophoresis. The theory is illustrated by using a system in which weak acids are separated by migrating against an H+ pulse. The mathematical description pertains to (i) the evolution and migration of the concentration profile of the H+ pulse, and (ii) the migration of a sample substance (here a weak acid) against and through the pulse. As a result the migration (detection) times of the separated sample components are obtained. Based on the theory, a graphical treatment was developed which allows fast optimization of the separation conditions by observing (on the PC monitor) how the trajectories of the substances (drawn in a time vs. distance coordinate system) change with a change in the parameters of the pulse. Some of the results illustrate the possible advantages of using the dynamic pulse method in analytical practice.

Acids↗
PubMed1989

Step change of counterion--a new option in capillary zone electrophoresis.

In contrast to common capillary zone electrophoresis, with a constant composition of the background electrolyte, a new method is described, based on a change of the ionic matrix composition during the migration of the sample components. The proposed method expands the scale of pK's of analyzed compounds in a single run and affords new potential for optimizing the separation. The step change of the ionic matrix composition was achieved by displacing the primary matrix by the modified ionic matrix (electrolyte) which migrated against the movement of the sample components. The separation thus proceeded in the primary ionic matrix (electrolyte) while the detection was performed in the modified matrix with resultant shortening of the analysis time and convenient quantitation. A model mixture of five compounds, with a difference of four units in pK could be well resolved.

Dinitrophenols↗
PubMed1988

Determination of oxalate in human serum by multicolumn isotachophoresis.

The practical usefulness of multicolumn isotachophoresis was demonstrated by the determination of oxalate levels in human serum. 10 mmol/L HCl and 100 mmol/L Na2HPO4 served as the leading and terminating electrolyte, respectively. For the stabilization of the isotachophoretic zones in large cross section channels a suspension of Bio-Gel P-300 in the leading electrolyte was used. For the analysis ca. 1 mL of fresh serum was required and 1.2 mL of 1:1 mixture of serum and the suspension of Bio-Gel P-300 in deionized water was applied as sample. The time of analysis ranged between 45-49 min. The detection limit of analysis was determined to be 50 nmol/L. Reproducibility of analysis of 1 mumol/L oxalate in water standard was found to be 2.6% (n = 6).

Electrophoresis↗
PubMed1985

Large sample volume preseparation for trace analysis in isotachophoresis.

An isotachophoretic device for the analysis of trace components in a sample with the efficient pre-separation and elimination of bulk components has been suggested and realized. A large volume of the sample in question is separated in a rectangular wide-bore channel packed with a suspension of a granulated polyacrylamide gel and analyzed in free electrolytes in a narrow-bore tube. Trace components, the concentrations of which are 10(-6) mol/l, can be analyzed in 60-70 min applying ca. 1 ml of the sample even in the presence of bulk excess of a major component the concentration of which is by 5 orders of magnitude higher.

Acrylic Resins↗
PubMed1976

Separation of some typical Krebs cycle acids by high-speed isotachophoresis.

In order to perform a required separation, an experimental procedure for the selection of suitable operating conditions is suggested and discussed. It is based on measurements of the dependences of the relative effective mobilities of the components under investigation on the pH of the leading electrolyte. The procedure was applied to a set of typical Krebs cycle acids and the values of the relative effective mobilities measured are given in tables and graphs. A pH of 3.8 was selected as the most suitable. At this value, the acids investigated were successfully separated in less than 4 min using 0.011 M hydrochloric acid + beta-alanine as the leading electrolyte.

Citric Acid Cycle↗