Capillary electrophoresis nonionic

Heinig, K., Vogt, C., Werner, G. (1998). Separation of nonionic surfactants by capillary electrophoresis and high-performance liquid chromatography. Anal. Chem. 70(9), 1885-1892. 

A contrast medium may be analyzed by conventional means for its iodine content and functionality or by capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) for its components. Nonionic... 

J. Li and J.S. Fritz, Nonaqueous media for separation of nonionic organic compounds by capillary electrophoresis. Electrophoresis, 20, 84—91, 1999. 

MEKC is usually used as a separation technique in which the basic properties of micellar liquid chromatography and CE are combined. MEKC was first described by Terabe in 1984 for the separation of nonionic aromatic compounds and is a powerful separation technique for lipophilic and nonionic species. By addition of surfactants to the background electrolyte, new options for solving electrophoretic separation problems are opened, but it is also possible to apply this technique to study the affinities of drug molecules to surface-active compounds. The term micellar affinity capillary electrophoresis (MACE) is used... 

Capillary zone electrophresis (CZE), one of the separation modes of capillary electrophoresis (CE), is a powerful separation technique for many ionic substances. CZE has a high resolution for ionic species but not for non-ionic species. For the separation of nonionic species, micellar electrokinetic current chromatography (MECC) can be applied. These CE methods are attractive tools for the determination of pyridine coenzymes because of their high separation efficiency, easy operation, and low running costs. 

Nonionics are not ideal candidates for capillary electrophoresis separation, since they are not mobile in an electrostatic field. In general, the separation is inferior to that obtained with HPLC analysis. On the other hand, CE is often easier to perform than HPLC, so there may be reason to apply CE for certain analyses when high precision and high resolution are not required. 

Capillary electrophoresis can be applied to nonionics if they are first made ionic by derivatization with, for example, phthalic anhydride (11,15). This has the additional benefit of making them detectable by UV absorbance. Excess derivatizing reagent results in a few minutes of unusable time at the beginning of the electropherogram as the reagent passes the detector. This is minimized if the excess reagent is removed by dialysis or solid phase extraction (16). 

TABLE 5 Capillary Electrophoresis Analysis of Nonionic Surfactants... 

Capillary zone electrophoresis also can be accomplished without an electroosmotic flow by coating the capillary s walls with a nonionic reagent. In the absence of electroosmotic flow only cations migrate from the anode to the cathode. Anions elute into the source reservoir while neutral species remain stationary. 

Wallingford, R.A. (1996). Oligomeric Separation of Ionic and Nonionic Ethoxylated Polymers by Capillary Gel Electrophoresis. Anal. Chem. 68(15), 2541-2548. 

Surfactants are amphophilic molecules, which consist of a hydrophobic carbohydrate part and a hydrophilic head group. In capillary zone electrophoresis (CZE), different types, i.e., anionic, cationic, but also neutral, tensides are employed. The ability of such molecules to interact with ionic and nonionic species has been used in ion chromatography and, in particular, in SDS-poly-(acrylamide) gel electrophoresis (PAGE) (15). 

Takayanagi, T. and S. Motomizu. 2007. Pseudo-homogeneous micelle extraction of ion-associates formed between tetrabutylammonium ion and some aromatic sulfonate ions into nonionic surfactant micelle studied through the mobility measurements in capillary zone electrophoresis. J. Chromatogr. A 1141 295-301. 

Abstract Surfactant mixtures are commonly used in many industrial applications. At the same time, the methods for surfactant analysis are rather laborious and often do not permit the determination of the individual surfactant content in mixed solutions. In the present work capillary zone electrophoresis (CZE) instrumentation was applied for the quantitative analysis of a cationic surfactant (dodecylpyridinium bromide) and a nonionic surfactant (Triton X-100) in aqueous solutions. The linear dependence of the analytical signal (electrophoregram peak area) versus the surfactant concentration was established for both surfactants over a wide concentration range. The analytical signal of an individual surfactant was... 

Wallingford, R. A., Oligomeric separation of ionic and nonionic ethoxylated polymers by capillary gel electrophoresis. Anal. Chem., 1996, 68, 2541—2548. 

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