Frans_M_Everaerts_Isotachophoresis_378342.pdf

It is very well known that charged particles move under the influence of an electric
field. Because the final velocity of such particles depends on numerous parameters, many
scientists through several decades have applied ths phenomenon to the characterization
and separation of a variety of charged particles, with a wide range of molecular weights,
both for analytical and preparative purposes.
Because the vital components of electrophoretic equipment need to be made of
insulating materials, in the early days it was a handicap for the further development of
electrophoretic instrumentation that modern insulating materials such as Perspex, PTFE
and fluoroethylene polymer were not available. Moreover, sensitive detection systems
had not been developed, so that the minimum detectable amount was rather high in
comparison with some other separation techniques.
After World War 11, the chemical industry began to show considerable interest in the
development of chromatographic separation techniques for the analysis of hydrocarbons
and other (complex) organic compounds. It may have bezn due to this development that
the materials for the construction of the vital parts of the electrophoretic equipment,
including the detectors, rapidly became available. Moreover, in the same period the
electronics industry also underwent a phenomenal expansion.
Although this book is devoted mainly to isotachophoresis, with which all kind of
charged molecules can be separated (as is shown in the Section Applications), the instrument
described can be used for other types of electrophoretic separations. Three main aspects
of isotachophoresis are covered, in three different sections.
In the first section, the theory of the isotachophoretic separation technique is given,
and other electrophoretic techniques are briefly described. For isotachophoresis, both a
simplified and a more complicated model are given. The latter model results in a computer
program suitable for the qualitative and quantitative interpretation of the analytical results.
In the Section Instrumentation, several detectors and the “isotachophoretic” equip-
ment are described. Also, a means is described of formulating a simplified model rapidly,
because for many problems simplified equipment is adequate. Moreover, not much cheap
equipment is commercially available yet.
In the last section, possible fields of application are considered. Analytical conditions
(so-called operational systems) are presented and results are given in the form of both
automatically recorded isotachopherograms and tables. The data in these tables can be
used for the qualitative interpretation of isotachophoretic analyses. Because all of the
values given were derived directly under the operational conditions considered, they
cannot be used for the calculation of, for example, mobilities at infinite concentration.
All of the isotachophoretic zones have a well defined temperature, pH and composition of
the electrolytes present, and these are constant in a chosen operational system but are
different from each other. For further theoretical approaches, corrections need to be made.
In the Appendices, a method is described for mobility determinations, the influence of
the diameter of the narrow-bore tube is dealt with and a list of relevant papers concerning
isotachophoresis is given.
Each section can be used almost independently by scientists interested in fundamental
aspects, by research groups who intend to construct an instrument and by scientists
whose main interest is in the analytical aspects.