Zone melting as an aid to impurity determination by thermal analysis

The determination of the impurity content of a sample by means of the meltingcurve method (calorimetric analysis) is often seriously hampered when solid soluble contaminants are present. Solid solutions often occur in substances purified by crystallization or extraction. A simple test on mixed crystals is described. When three or more impurities are present the relations obtainable from a melting curve are insufficiently accurate for computing the unknown concentrations and distribution coefficients to an acceptable extent. Only melting curves obtained from samples containing one or two impurities permit an exact, simple interpretation. A complex of impurities may be analysed when the sample is subjected to zone melting and a set of melting curves is obtained for parts of the ingot.     

Isotopes as tracers in analytical chemistry

A survey is given of the availability of radioactive and of concentrated heavy isotopes in Holland and of the instruments for their measurements.The principles of the application of tracers in analytical chemistry are reviewed and examples of the different kinds are described. Finally the determination of elements by induced radioactivity and by neutron absorption is dealt with.     

Green analytical chemistry as an integral part of sustainable education development

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Chemistry as a branch of analytical chemistry

Summary An approach to the teaching of chemistry and of analytical chemistry is presented, suitable for use at the 2nd or 3rd year level. The present tendency to subdivide chemistry into many small units is countered by this suggestion to use a comprehensive course on analytical chemistry as a means of reuniting the subdivisions of modern chemistry.

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Chemie als Zweig der analytischen Chemie

Zusammenfassung Der Unterricht in Chemie und analytischer Chemie des 2. oder 3. Studienjahres wird von einem neuen Gesichtspunkt aus gesehen: der heutigen Tendenz, Chemie in diverse Teilgebiete zu zergliedern, wird der Vorschlag eines allgemeinen Lehrganges in analytischer Chemie entgegengestellt, mit dessen Hilfe eine Wiedervereinigung der Teilgebiete der modernen Chemie erzielt werden kann.

Lecture presented at Euroanalysis I Conference, 28. 8.–1. 9. 1972 in Heidelberg, Germany.     

Zone melting and column crystallization as analytical tools

The techiniques of normal freezing, zone melting and column crystallization are discussed ; special attention is given to micro zone melting. The preparation of absolutely pure benzene by column crystallization is shown to be possible. Many examples of the utilization of these techniques are given, including work on isomeric compounds, plant and animal products and meteorite samples.     

Effluent analysis in analytical chemistry: an overview

This review summarizes and discusses effluent analysis, focusing on the methods and techniques that have been most frequently described in the literature since 1975. The methods are classified into four main categories: (1) physical and chemical properties; (2) inorganic metals analysis; (3) inorganic non-metallic analysis; (4) organic analysis.     

The analytical laboratory computer as a management aid

Intelligent use of the data available in the store of the analytical laboratory computer can provide much of the information necessary for the optimization of laboratory resources. The research manager can use such information to monitor the activity of various projects and the cost effectiveness of the analytical service.     

Porphyrins in analytical chemistry. A review

The porphyrins, naturally occurring macrocyclic compounds, have, in the last 10 years, gained increasing interest in analytical chemistry. This review based on 123 original literature references, mostly published in the 1990s, presents catalytic applications of metalloporphyrins in electroanalysis as electroactive agents in ion selective membranes, as unique reagents in spectrophotometry and as new stationary phases offering unusual resolution in HPLC. The collected data are also presented in four tables.     

Glassy carbon as electrode material in electro- analytical chemistry

The review is based on a literature search through Chemical Abstracts and the Science Citation Index. The topics covered are: chemical and electrochemical aspects of the glassy carbon/electrolyte interface for both aqueous solutions and non-aqueous electrolytes; analytical applications of glassy carbon electrodes, including voltammetry, stripping voltammetry, amperometry coulometry, potentiometry and chronopotentiometry; flow-through detectors; chemically modified glassy carbon electrodes; electrosynthesis; and pretreatment techniques.     

Research on analytical chemistry in Brazil: an overview

An overview is presented of the beginnings, evolution and current status of research on analytical chemistry in Brazil. Among the various fields of chemistry two decades ago, Analytical Chemistry was considered one of the least developed in Brazil. In the last 15 years, however, research and development in this field have expanded considerably and today it is one of the most highly developed fields of Chemistry in Brazil. This paper offers a general overview of this evolution and some suggestions for possible routes for the future of analytical chemistry in Brazil.     

Nucleation in analytical chemistry

Precipitation involves two processes, nucleation and subsequent crystal growth. The nucleation process is of extreme importance in determining the number and size of the final crystalline particles. The significance of experimental studies of nucleation is discussed and the need for further research indicated.     

Chemiluminescence in analytical chemistry

Analytical applications based on chemiluminescence are reviewed. Analyses in the gas phase for atmospheric pollutants such as sulphur compounds, ozone and oxides of nitrogen are described. The commonest chemiluminescent systems used in the liquid phase are then discussed. Their applications as indicators in different types of titration are outlined. Determinations of organic and inorganic substances are classified according to their action as oxidant, catalyst or inhibitor. Special applications are described in fields such as forensic science, microbiology, polymer technology, radiation chemistry and flow mechanics.