Problems In Analytical Chemistry Research Articles

High purity fluoropolymer materials: Trace element content and leaching

Many problems in analytical chemistry are shared by the high purity crystal growth community since both are greatly concerned with the effects of impurities either upon an analysis or upon a device. Fluoropolymers are widely used today in applications where inertness or high purity or both are needed. The behavior of these polymers in high purity solvent systems has been investigated by several analytical techniques. Both the resin from which finished parts are made as well as blow molded bottles have been evaluated to determine cationic impurities in both the resin and in leachates.

Kalman filtering approaches for solving problems in analytical chemistry

The application of the Kalman filter to the solution of a variety of problems in analytical chemistry is reviewed. Five examples are selected from the literature to illustrate the use of Kalman filtering techniques for obtaining least-squares estimates fo several parameters of analytical importance. These examples include multicomponent curve resolution and concentration estimation, correction for variable background responses, calibration with drift compensation, and estimation of kinetic parameters for first-order reactions and for heterogeneous charge-transfer reactions. An adaptive Kalman filtering technique is required for the solution of the background correction problem, and the extended Kalman filter algorithm is required for the solution of the nonlinear kinetic problems. For each case, the results that were obtained are summarized, and some advantages of Kalman filtering over traditional least-squares approaches are discussed.

Analytical applications of reversed-flow gas chromatography

The technique of reversed-flow gas chromatography can be used to solve problems in analytical chemistry, e.g., measurement of the broadening factors in gas chromatography, calibration of gas chromatographic detectors, measurement of activity coefficients and non-equilibrium headspace analysis. The method is basically a kinetic technique, but using the rates of physical processes rather than the rates of chemical reactions. It is a flow perturbation method, based on reversing the direction of flow of the carrier gas for definite time intervals. The experimental set-up is very simple and needs only a slight modification of a conventional gas chromatograph, equipped with any kind of detector.

Coprecipitation of Calcium and Barium Carbonates by Carbon Dioxide Gas at 80° C

The coprecipitation of calcium and barium carbonates was investigated as a problem in analytical chemistry. Carbon dioxide gas was introduced into solutions of calcium and barium at 80°C. The particles produced were composed of rod-shaped, spindle-shaped and cubic-shaped crystals. The composition of calcium and barium in the reaction mixture changed with bubbling period of carbon dioxide gas. The shape of particles was dependent on the composition of residual calcium and barium in the reaction mixture. The particles were solid solutions of calcium and barium carbonates, whose crystal structures were a little different from each other.

Failures and successes with pattern recognition for solving problems in analytical chemistry

In our laboratory, pattern recognition has been used for solving a variety of problems. The purpose of this paper is to demonstrate the potential of this technique in analytical chemical laboratories. Two very different examples are given, one resulting in a temporary failure, another ending succesfully. References to other problems that have been solved in our laboratory are also given.

Trends in using resilient polyurethane foams as sorbents in analytical chemistry

Considerable progress has been made in recent years in the application of polyurethane foams to separation and preconcentration problems in analytical chemistry. The results published in the years 1979 to 1982 have been collected and are presented in tabulated form.

A multivariate calibration problem in analytical chemistry solved by partial least-squares models in latent variables

The use of partial least squares in latent variables (PLS) for multivariate calibration problems is described. The application is the simultaneous determination of ligninsulfonate, humic acid and an optical whitener, from their severely overlapping fluorescence spectra. The predictive performance of the resulting calibration model is tested with a separate set of samples. The PLS method also identifies samples which do not fit the calibration model. The PLS method is compared with principal components analysis combined with multiple regression.

Compensation for drift and interferences in multicomponent analysis

Abstract : The detection and subsequent correction of drift in an analytical signal occurring during the course of an analysis is a common problem in analytical chemistry. In this paper, a solution to this problem is presented in the form of an extension to the theory of the Generalized Standard Addition Method (GSAM), a method currently used to simultaneously correct for matrix effects and interferences in multicomponent analysis. (Author)

Analytical Chemistry in chemical education in the Federal Republic of Germany

The various tasks and problems of Analytical Chemistry and the connections with all ranges of life are shown by means of a graphical representation according to H. Kelker. Training facilities in Analytical Chemistry are differing at the individual universities. Several universities offer the possibility of studying this field more thoroughly. The situation at the University of Tubingen is described as an example.

The Fourth Theophilus Redwood Lecture. Polarography in attacking practical and theoretical problems in Analytical Chemistry

Download options Please wait... Article information DOI https://doi.org/10.1039/AD9751200199 Article type Paper Download Citation Proc. Anal. Div. Chem. Soc., 1975,12, 199-208 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions The Fourth Theophilus Redwood Lecture. Polarography in attacking practical and theoretical problems in Analytical Chemistry P. Zuman, Proc. Anal. Div. Chem. Soc., 1975, 12, 199 DOI: 10.1039/AD9751200199 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Petr Zuman

The analytical chemistry of mixed ligand complexes

Mixed ligand complexes are characterized by their extreme stability. The chemical individuality of the central atom displays itself clearly, and peculiarities in extractions with organic solvents may be observed. Such properties open new routes to the solution of various theoretical and practical problems in analytical chemistry; true mechanisms and kinetics of analytical reactions can be elucidated and the selectivity and sensitivity of analytical methods can be improved. The process of complex formation and the properties of mixed complex compounds containing inorganic ligands are considered with reference to the platinum group elements. The formation of mixed complexes containing organic and inorganic ligands sometimes determines the mechanism of the analytical reaction and the composition of the end product; examples of such interaction are given. The sensitivity and selectivity of analytical methods can be improved by means of the formation of complex compounds of the ionassociate type, and unusual methods of separation and group concentration can be achieved. The study of mixed chelates has developed in two directions: (a) studies of improved extractability (synergy), and coextraction of elements as mixed chelates; and (b) studies of changes in the physicochemical properties of systems, e.g. absorbance and fluorescence. Various new analytical procedures are discussed. INTRODUCTION Developments in the field of coordination chemistry, which is closely bound up with the study of mixed and mixed polynuclear complexes, have been very extensive in recent years. A study of mixed ligand complex formation is of extreme interest to analytical chemists for the following reasons. 1. Mixed ligand complexes are the most general and probable form of existence of the elements in solution. 2. Studies of mixed ligand complex formation make it possible to estimate the characteristics of the intermediate and final forms of the complexes, and therefore to comprehend the mechanism and kinetics of analytical reactions. 3. Certain peculiarities of elements, which are most pronounced in mixed ligand complexes, as well as the physical phenomena accompanying the process of mixed ligand complex formation, open new prospects for the development of selective and sensitive methods for the determination, separation and concentration of elements. The quantitative

A Chromatographic Separation of Meta- and Para-Cresols

THE separation of isomers has always been a major problem in analytical chemistry. In the case of meta -and para-cresols, this difficulty is a very real one, for in the absence of spectroscopic apparatus there is no available method for determining both these components.

Die Wissenschaftlichen Grundlagen der analytischen Chemie

THE appearance of a fifth edition of this well-known book affords gratifying evidence of the widespread recognition that the study of analytical processes from the theoretical point of view is a necessary adjunct to the practical work of the laboratory. At the same time, the continued demand for a book of this character is a striking testimony to the general utility of the ionic hypothesis in the consideration of the problems of analytical chemistry. In spite of the many attacks, persistent and vigorous, which have been made upon the theory of Arrhenius, it has to be admitted that its position as a working hypothesis is stronger to-day than it was at the time of issue of the first edition of this volume. Die Wissenschaftlichen Grundlagen der analytischen Chemie. By W. Ostwald. Fünfte Auflage. Pp. xii + 233. (Leipzig: W. Engelmann, 1910.) Price 8 marks.