Over the last decade, high performance Capillary electrophoresis (HPCE) has emerged as a powerful and versatile separation technique that promises to rival high performance liquid chromatography when applied to the separation of both charged and neutral species. The high speed and high separation efficiency which can be attained using any of the various modes of HPCE has resulted in the increased use of the technique in a range of analytical environments. The procedures are, however, still in the early stages of development and several barriers remain to their adoption as the technique of choice for a range of analytical problems. One such barrier is the selection and optimization of the conditions required to achieve reproducible separations of analytes and it is in this area that this new book seeks to give assistance. The book is written by an international team of authors, drawn from both academic and industrial users, and the manufacturers of instruments. At its heart are a number of tables, divided into specific application areas. These give details of published separations of a wide range of archetypal analytes, the successful separation conditions and the matrix in which they were presented. These tables are based on separations reported since 1992 and are fully referenced to the original literature. The tables are supported by discussions of the problems that a particular area presents and the strategies and solutions adopted to overcome them. The general areas covered are biochemistry, pharmaceutical science, bioscience, ion analysis, food analysis and environmental science.

More than ten years have elapsed since the publication of a compre hensive review on the quassinoids, the bitter principles of the Simaroubaceae family (80). Interest in these terpenoids has increased enormously in recent years due in part to the finding of the American National Cancer Institute in the early 1970s that these compounds display marked antileukemic activity. Furthermore, a wide spectrum of other biological properties for the quassinoids has been discovered and studies on chemical modifications of inactive members to yield biologically active ones were undertaken. New structures have been established also and numerous synthetic approaches have been developed which include the total synthesis of the parent compound, quassin (p. 250) and also that of castelanolide (p. 253). It is intended that this present chapter will be an extension of my first review in this series and will contain references up to September 1984. A short article on some aspects of this subject was published recently (81). II. Quassinoid General Features In reviewing the essential features of the quassinoids, the new structural types discovered during the last decade will be emphasised. The quassinoids can be divided into distinct groups according to their basic skeletons. The five skeletons observed are presented on Chart 1."

Over the last decade, high performance Capillary electrophoresis (HPCE) has emerged as a powerful and versatile separation technique that promises to rival high performance liquid chromatography when applied to the separation of both charged and neutral species. The high speed and high separation efficiency which can be attained using any of the various modes of HPCE has resulted in the increased use of the technique in a range of analytical environments. The procedures are, however, still in the early stages of development and several barriers remain to their adoption as the technique of choice for a range of analytical problems. One such barrier is the selection and optimization of the conditions required to achieve reproducible separations of analytes and it is in this area that this new book seeks to give assistance. The book is written by an international team of authors, drawn from both academic and industrial users, and the manufacturers of instruments. At its heart are a number of tables, divided into specific application areas. These give details of published separations of a wide range of archetypal analytes, the successful separation conditions and the matrix in which they were presented. These tables are based on separations reported since 1992 and are fully referenced to the original literature. The tables are supported by discussions of the problems that a particular area presents and the strategies and solutions adopted to overcome them. The general areas covered are biochemistry, pharmaceutical science, bioscience, ion analysis, food analysis and environmental science.

Die Befruchtung spielt eine bedeutende Rolle im Entwicklungsgang der Organismen. In ihrem Verlauf werden die Gametenkerne, und damit das genetische Material zweier Individuen, vereinigt. Durch die Meiose (Reduktionsteilung) wird der Ausgangszustand wiederhergestellt, jedoch in einer solchen Weise, daB die elterlichen Erbfaktoren in den verschiedensten Kombinationen neu verteilt werden konnen. Die Beob- achtung von Befruchtungsvorgangen zeigt, daB der eigentlichen Ver- schmelzung der Geschlechtszellen Reaktionen vorausgehen, an denen offensichtlich chemische Wechselwirkungen beteiligt sind. Besonders deutlich lassen sich solche stoffiichen Wechselwirkungen bei niederen Pflanzen beobachten, bei denen beispielsweise Geschlechtsorgane nur gebildet werden, wenn der entsprechende Partner oder Filtrate seines Kulturmediums vorhanden sind. In anderen Fallen kann man beobachten, daB Geschlechtsorgane durch Luft oder Wasser gerichtet aufeinander zu- wachsen oder, daB freibewegliche mannliche Gameten sich gezielt zu stationaren weiblichen Gameten hinbewegen. Solche biologischen Reak- tionen sind auBerordentlich empfindlich, und die Konzentration der beteiligten Stoffe ist entsprechend gering. Dies macht die Ansammlung von gentigenden Mengen fUr die StrukturaufkIarung zu einem auBerst mtih- samen Unternehmen. Obwohl auch in der alteren Literatur zahlreiche Hinweise auf chemische Wechselwirkungen zwischen Sexualpartnern vor- handen sind (42, 43), konnten bisher erst wenige derartige Geschlechts- stoffe identifiziert werden. Erst die hochleistungsnihigen modernen Ana- lysenmethoden, wie Massen- und Kernresonanz-Spektroskopie, haben hierbei die Forschung wesentlich vorangetrieben. Man kennt heute die Molekularstruktur von vier Sexualhormonen, die nunmehr auch synthe- tisch zuganglich sind.