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M M Dittmann

Publications and source records attributed to M M Dittmann.

4 recordsLinked to original sources
PubMed2000

Separation of basic solutes by reversed-phase capillary electrochromatography.

The separation of basic solutes at low pH by capillary electrochromatography (CEC) has been investigated. The feasibility of separation of basic solutes by CEC was demonstrated. Influence of operational parameters, solvent composition, pH, temperature on retention and selectivity of the separation of a mixture of basic, neutral and acidic drug standards has been investigated. The observed elution behavior has been modeled to account for both chromatographic retention and differential electrophoretic mobility of the solutes. This model was verified experimentally. It is demonstrated in this work that the elution window of solutes in reversed-phase CEC is expanded to range from -1 to infinity.

Acetonitriles↗
PubMed2000

Towards the column bed stabilization of columns in capillary electroendosmotic chromatography. Immobilization of microparticulate silica columns to a continuous bed.

This article discusses a novel method generating a continuous bed inside the CEC column. The column bed composed of microparticulate reversed-phase silica is completely immobilized by a hydrothermal treatment using water for the immobilization process. This process eliminates the manufacture of frits of both ends of the column and all problems associated with their preparation. Fundamental studies on operational parameters will be presented such as the dependence of the immobilization on the column temperature, the type of stationary phase and the column back pressure. The immobilized CEC columns show the same high column efficiency as packed columns with frits.

Electrophoresis, Capillary↗
PubMedDate not supplied

Advances in capillary electrochromatography.

This paper presents practical aspects of capillary electrochromatography (CEC). Preparation of capillary columns, including terminating frits and immobilization of the packed bed, is described in detail. Longevity and reproducibility of CEC columns is demonstrated. Instrumental aspects, sample introduction, sensitivity of detection, and gradient elution are discussed in detail. A number of examples that illustrate the versatility of CEC, in particular, for providing an isocratic separation alternative to conventional gradient separation in HPLC, are given.

Chromatography↗