Recent scientific and industrial developments have demon­ strated the major effects (advantageous or otherwise) of trace components in compounds, which in commercial products may substantially affect the properties and the course of reactions, especially catalytic ones. Some of these problems (e.g., the pur­ ity of natural waters and air) have attracted the attention not only of specialists but also of society generally. It would be impossible to do research on trace components and contaminants if we did not have reliable rapid and sensitive methods of determining substances present in mixtures in minute concentrations. Gas chromatography is an effective method of purity testing. This book deals with analysis for trace components, together with the basic methods of gas chromatography that are used for the purpose. We have tried to reflect here the principal papers in this area appearing in the foreign literature and in Rus­ sian. Weare indebted to Plenum Pre~'B for the opportunity of pre­ senting this edition. Moscow September 1972 v Preface Gas -chromatographic analysis for impurities is presently a rapidly developing area in gas chromatography, because many practical topics give considerable importance to impurity analy­ sis. Progress in this analysis bas been such for volatile com­ pounds (and also for nonvolatile ones, when reactive gas chroma­ tography is used) that one can now be confident of solving most practical problems in this way. Commercial ionization detectors of high sensitivity and selectivity often allow one to detect impuri­ ties down to levels of parts in 109.