Chromatographic Retention Indices

Focusing on the identification of substances on the basis of their retention, this volume pays particular attention to methods for attaining optimum conditions in order to obtain reliable values of retention times. It features tables which summarize over 1500 values of retention indices.

This book presents an update on the basics, trends and achievements of chemometric methodology required to study the relation between the chemical structure of solutes and their retention in various chromatographic systems. The author critically analyzes hundreds of relevant papers published during the past two decades. In this period, chemometrics has evolved into an established research and practice area of interest to scientists ranging from chromatographers to environmental and medicinal chemists. Although emphasis is placed on the more recent findings, readers will also find the basic theories required to solve specific problems. It should prove advantageous for contemporary chemists and related scientists if they switch from thermodynamics - in practice often inappropriate - to a statistically based (and limited) chemometric approach.

International experts have compiled data on some 5000 substances (an astounding expansion compared to the 600 and 1100 substances covered in the first and second editions respectively). The enlarged data base has been made possible by combining the extended DFG-TIAFT data base with the one developed by Pfleger, Maurer and Weber. The latter has been generated mainly on capillary columns and includes many toxicologically relevant metabolites seen in actual intoxications. The more polar substances, which are difficult to chromatograph, were derivatized before retention index measurement. In addition, data on a number of important substance classes such as pesticides, beta-blockers, benzodiazepines doping agents and non-steroidal antiinflammatory drugs were considerably extended. Moreover, this new edition also covers modern capillary gas chromatography.

This book brings together a number of studies which examine the ways in which the retention and selectivity of separations in high-performance liquid chromatography are dependent on the chemical structure of the analytes and the properties of the stationary and mobile phases. Although previous authors have described the optimisation of separations by alteration of the mobile phase, little emphasis has previously been reported of the influence of the structure and properties of the analyte. The initial chapters describe methods based on retention index group increments and log P increments for the prediction of the retention of analytes and the ways in which these factors are influenced by mobile phases and intramolecular interactions. The values of a wide range of group increments in different eluents are tabulated. Different scales of retention indices in liquid chromatography are described for the comparison of separations, the identification of analytes and the comparison of stationary phases. Applications of these methods in the pharmaceutical, toxicology, forensic, metabolism, environmental, food and other fields are reviewed. The effects of different mobile phases on the selectivity of the retention indices are reported. A compilation of sources of reported retention index values are given. Methods for the comparison of stationary phases based on the interactions of different analytes are covered, including lipophilic and polar indices, shape selectivity comparisons, their application to novel stationary phases, and chemometric methods for column comparisons.

The use of computers in numerical characterization of molecular structures has given chemists fundamentally new information on chemical structures, leading to major developments in physical, analytical, and medicinal chemistry. This book, written by a pioneer in the field, extends and updates research on quantitative structure retention relationships (QSRR) by consolidating and critically reviewing the extensive literature on the subject while providing basic theoretical and practical information required in all investigations involving chromatography, analytical chemistry, biochemistry, and pharmaceutical research. Coverage includes detailed discussions of the general theories and mechanisms of chromatographic separations, prediction of retention coefficients, statistical techniques and formal requirements of QSRR studies, specific applications of chromatographic data, and much more. Also provides several carefully selected figures and tables plus extensive bibliographies.

Introduction to essential oil analysis. some aspects of essential oil preparation. considerations on the selection of cappilary columns for essential oil analysis. microtechniques in essential oil analysis. headscape versus classical analysis. Fingerprints in essential oil analysis. industrial quality control of essential oil by capillary GC. Retention indices in essential oil analysis. Possibilities and results of dual channel analysis of essential oils with fused silica capillaru columns. GC- mass specytrometry of essential oils: positive ion and negative ion and negative ion chemical ionazation techniques,computer matching techniques. Examples of artefact formation by chromatographic techniques. Possibilities, limitations, and future develpments in GC-FTIR analysis of essential oils. Possibilities of multidimensional GC in essential oils.

This new publication is the latest result of further fruitful cooperation between the Committee for Systematic Toxicological Analysis of TIAFT and the Senate Commission for Clinical-Toxicological Analysis of the DFG. It provides reliable gas chromatographic retention indices for volatile substances frequently encountered in analytical toxicology. It is the first book of its kind that contains data bases for two different types of Carbowax columns, one based primarily on adsorption chromatography, the other on partition chromatography. The retention values for some 300 toxicologically relevant volatile substances are given as Retention Indices, using n-alcohols as reference standards (methanol, ethanol, n-propanol-1, etc.). The data bases cover the large majority of volatiles used in the laboratory, in industry, in household products and in solvent abuse.