Tarso B. Ledur Kist - Open and Toroidal Electrophoresis

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Open and Toroidal Electrophoresis: краткое содержание, описание и аннотация

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Presents the theory and applications of Toroidal Capillary, Microchip, and Slab Electrophoresis to analytical chemists across a range of disciplines Written by one of the developers of Toroidal Capillary Electrophoresis (TCE), this book is the first to present this novel analytical technique, in detail, to the field of analytical chemistry.
The exact expressions of separation efficiency, resolution, peak capacity, and many other performance indicators of the open and toroidal layouts are presented and compared.
Featuring numerous illustrations throughout,
offers chapters covering: Solvents and Buffer Solutions; Fundamentals of Electrophoresis; Open Layout; and Toroidal Layout. Confronting Performance Indicators is next, followed by chapters on High Voltage Modules and Distributors; Heat Removal and Temperature Control; and Detectors. The book finishes with an examination of the applications of Toroidal Electrophoresis.
The first book to offer a detailed account of Toroidal Electrophoresis—written by one of its creators
Compares the toroidal layouts with the well-established open layouts of the three most used platforms (Capillary, Microchip, and Slab) Provides solutions to many of the experimental issues arising in electromigration techniques and discusses the voltage distributors and detectors that are compatible with the toroidal layouts Richly illustrated with a large number of useful equations showing the relationships between important operational parameters and the performance indicators 
is aimed at method developers and separation scientists working in clinical analysis, and food analysis, as well as those in pharmacology, disease biomarker applications, and nucleic acid analysis using the Capillary, Microchip, or slab Platform. It will also benefit undergraduate and graduate students of inorganic analytical chemistry, organic analytical chemistry, bioanalysis, pharmaceutical sciences, clinical sciences, and food analysis.

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These allow the content of H 3O +to be known in many more units (including, but not limited to, molar, molal, and g Open and Toroidal Electrophoresis - изображение 143) and with much higher precision as more parameters of Open and Toroidal Electrophoresis - изображение 144(with Open and Toroidal Electrophoresis - изображение 145) become available.[8]

Small molecules carrying an acid and/or a basic group tend to be soluble in pure water and exhibit a certain degree of ionization ( Section 1.1.6) or dissociation ( Section 1.1.5). The ionization or dissociation of the acid HA in aqueous solutions (H 2O + HA A −+ H 3O +) at a given temperature is characterized by the acid ionization constants and They are defined as 114 where - фото 146and They are defined as 114 where is the activity of the spec - фото 147. They are defined as:

(1.14) where is the activity of the species The activity of water is approx - фото 148

where картинка 149is the activity of the species Open and Toroidal Electrophoresis - изображение 150. The activity of water is approximately constant at a given temperature and with the low solute concentrations normally used in the ESTs. Therefore, it is assumed that Open and Toroidal Electrophoresis - изображение 151. Equivalently, the conjugated acid BH +of base B, produced by the equilibrium reaction H 2O + BH + B + H 3O +, has the following acid ionization constants:

(1.15) Open and Toroidal Electrophoresis - изображение 152

These acid ionization constants are better represented by Open and Toroidal Electrophoresis - изображение 153, where Open and Toroidal Electrophoresis - изображение 154.

The картинка 155ranges defined for very strong ( картинка 156), strong ( картинка 157), medium, weak, and very weak acids are poorly defined. Nevertheless, it is safe to say that acids with a картинка 158of between 4 and 10 are weak acids and that acids with картинка 159can be considered as very weak acids. The opposite occurs for bases, as for a base to be very strong the картинка 160of the conjugated acid BH +( equation 1.15) must be above 14 ( картинка 161), with strong bases exhibiting картинка 162. Similar to weak acids, weak bases also exhibit картинка 163of between 4 and 10; however, in this case the very weak bases exhibit картинка 164.

It is important to note that Open and Toroidal Electrophoresis - изображение 165significantly changes with temperature for some functional groups: Open and Toroidal Electrophoresis - изображение 166, where картинка 167is expected to be a smooth and slowly varying function of temperature. The картинка 168of the great majority of amines decreases with temperature, while carboxylic acids exhibit a much smaller change, usually negative, but there are some exceptions and it depends on the temperature range. These temperature sensitivities have important practical implications for method development within the field of ESTs, as they affect the mobility of the analytes and the pH of the buffers.[9–11] Moreover, they are used to promote cyclic band compression in the toroidal layouts, which is an interesting way to get some control of band spreading along the separation mediums (see Appendix G).

1.1.10 Concentration–pH and pa–pH Diagrams

It is important to know the concentration of all chemical species present in a given buffer solution at a given pH, because some species may interfere with the migrating analytes under study. Additionally, it is also important to know the concentrations of all existing species of an analyte present in a separation medium at a given buffer pH. This is important because the analyte species present define the average electrophoretic mobility of the analyte, the system peaks, and the interactions of the species with the BGE components. Open and Toroidal Electrophoresis - изображение 169–pH diagrams are one of the most commonly used tools to visualize the concentration of chemical species, showing the concentration of each species at every pH in the Open and Toroidal Electrophoresis - изображение 170range (which is the maximum range used in ESTs). Figure 1.4shows the картинка 171–pH diagram of a triprotic acid (0.1 M citric acid in an aqueous solution), which is a complex acid because its successive ionizations produce many species. In Figure 1.4only the most concentrated species can be seen, as the curves of the most diluted species (with картинка 172M) run too close to the line at картинка 173M to be observed. Nevertheless, many detectors (fluorescence and potentiometric) are able to detect species down to картинка 174M and even lower concentrations. Therefore, sometimes it is desirable to visualize the concentration profiles of species within lower concentration ranges. p картинка 175–pH diagrams are ideal for this as they show картинка 176as a function of pH. Figure 1.5shows the same case as studied in Figure 1.4( Open and Toroidal Electrophoresis - изображение 177–pH diagram of citric acid at the initial concentration of Open and Toroidal Electrophoresis - изображение 178M), but it is now represented as a p pH diagram Figure 14 cpH diagram of citric acid species in an aqueous - фото 179–pH diagram.

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