Vladislav Dolník

Capillary electrophoresis on microchip.

Capillary electrophoresis and related techniques on microchips have made great strides in recent years. This review concentrates on progress in capillary zone electrophoresis, but also covers other capillary techniques such as isoelectric focusing, isotachophoresis, free flow electrophoresis, and micellar electrokinetic chromatography. The material and technologies used to prepare microchips, microchip designs, channel geometries, sample manipulation and derivatization, detection, and applications of capillary electrophoresis to microchips are discussed. The progress in separation of nucleic acids and proteins is particularly emphasized.

Polymer wall coatings for capillary electrophoresis

This review article describes the preparation of dynamic and static polymeric wall coatings for capillary electrophoresis. Properties of bare fused‐silica surfaces and methods for the characterization of capillary coatings are summarized. The preparation and basic properties of neutral and charged wall coatings are considered. Finally, advantages and potential applications of various coatings are discussed.

Capillary electrophoresis of proteins 1999-2001.

This review article with 223 references describes recent developments in capillary electrophoresis (CE) of proteins and covers papers published during last two years, from the previous review (V. Dolník, Electrophoresis 1999, 20, 3106–3115) through Spring 2001. It describes the topics related to CE of proteins including modeling of the electrophoretic properties of proteins, sample pretreatment, wall coatings, improving selectivity, detection, special electrophoretic techniques, and applications.

Recent developments in capillary zone electrophoresis of proteins.

This review article with 125 references describes recent developments in capillary zone electrophoresis of proteins. It encompasses approximately the last two years, from the previous review (V. Dolník,Electrophoresis 1997, 18, 2353—2361) through Spring 1999. Topics covered include modeling of the electrophoretic properties of proteins, sample preconcentration and derivatization, wall coatings, improving selectivity, special detection techniques, and applications.

Recent devepolments in isotachopresis

Abstract This paper is summarizing the contributions to the analytical capillary isotachophoresis published during the period 1981–1984. It characterizes the present state of the method and covers theory, fundamental analytical aspects, instrumentation and applications. Special attention was payed to the fundamental analytical aspects, and a detailed discussion is given of the selection of electrolyte systems, stability of zones and separability of substances. The present commercial instrumentation is also briefly described.

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.

Wall coating for DNA sequencing and fragment analysis by capillary electrophoresis

In capillary electrophoresis, covering the inner capillary surface with a coating is an efficient way to minimize both the electroosmotic flow and sorption of w analytes on the capillary wall. We modified the procedure by Cobb et al. Anal. . x Chem. 62, 2478 1990 for preparing wall coating to permit large-scale production. Specifically, we use a positive pressure to fill the capillary with both thionyl chloride and later vinylmagnesium bromide solution. This enables large-scale production of the coating by treating 100 m capillary pieces at a time. We found that no extensive flushing with either organic solvents or sodium hydroxide is needed before the reactions are performed. Application of liquid thionyl chloride with positive pressure scavenges residual humidity on the capillary surface and eliminates a need for extensive drying of the capillary. In the polymerization step, elimination of TEMED from the polymerization mixture and incubation at 708C enables a homogeneous coating to be prepared in capillaries as long as 100 m. The prepared wall coating is stable for approximately 110 runs of DNA sequencing in a denaturing matrix and over 300 runs of DNA fragment analysis under nondenatur- ing conditions. Q 1998 John Wiley & Sons, Inc. J Micro Sep 10: 175)184, 1998

CAPILLARY ELECTROPHORESIS IN SIEVING MATRICES : SELECTIVITY PER BASE, MOBILITY SLOPE, AND INFLECTION SLOPE

We compare the migration behavior of DNA sequencing fragments in hydroxyethyl cellulose (HEC) to the theoretical model of migration in the reptation mode. Good agreement was found for the mobility curve. We derived empirical equations for the relationship between selectivity per base and sieving matrix concentration and between the mobility slope and matrix concentration. We propose the inflection slope, i.e., the slope of the log‐log mobility curve at its inflection point, as the quantitative parameter of sieving performance.

Galactomannans as a sieving matrix in capillary electrophoresis.

Purification of galactomannans including guaran, tara gum, and locust bean gum is described as well as their use as a sieving matrix in DNA sequencing by capillary electrophoresis (CE). Three methods of galactomannan purification were developed and tested using guaran. The first method is based on hydrolysis of proteins using alkali treatment and precipitation of guaran with acetone. The second method uses ion‐exchange resins QAE Sephadex A‐25 and SP Sephadex C‐25 together with acetone precipitation. The third method is similar to the second one, except that it uses ion‐exchange resins based on polystyrene, Source 30Q and Source 30S. Capillary zone electrophoresis of acetonitrile extracts from guaran revealed 4—5 characteristic major peaks and several minor peaks. Guar gum from different suppliers differed in the content of proteins. In purified guaran, protein peaks were detectable only using a 300‐fold concentrate of extract. The content of proteins in the guaran purified using the third method was 0.001% m/m as determined by CE. The weight average molecular mass of purified guaran can be as large as 2.2 × 106. The purified galactomannans were used as a sieving matrix in DNA sequencing by CE. M13 DNA was sequenced to read lengths of about 600 bases in less than 90 min. Separation efficiencies exceeded 1 million theoretical plates for DNA fragments shorter than about 600 bases.

Selectivity, differential mobility and resolution as parameters to optimize capillary electrophoretic separation

Selectivity, differential mobility, and resolution have been tested as the optimization functions to find the optimum pH of operational electrolyte for separation by capillary electrophoresis when organic acids occurring in human serum have been selected as a model mixture for computer simulations. Using tabulated values of ionic mobilities and pKa values, either selectivity or differential mobility or resolution for the hardest-to-separate pair of separands are calculated and plotted vs. pH. The optimum pH is the pH value, at which the optimization function reaches its maximum.