When the list of organic priority pollutants was first published, many mass spec­ troscopists went scrambling to their reference books. GC-MS was mandated for the analysis of 114 compounds, yet the spectra of many of them, if they had been recorded at all, were scattered throughout the literature. Moreover, it soon became apparent that, even if a sufficient number of instruments could be made available to undertake the task of monitoring 114 substances in the effluents of 21 categories of industry, the personnel could not be trained to perform the analyses and interpret the results. The solution to this problem has been the development of highly automated mass spectrometers which can be operated by personnel without the traditional research training. This book is for the new breed of mass spectroscopist who is not interested in the esoteric details of mass spectral fragmentation, but who merely wishes to identify specific pollutants in effluents. Our inclusion of comprehensive lists of synonyms and bibliographic data should make the book of even greater value to the reader who is not too familiar with the idiosyncrasies of chemical nomenclature and the scientific literature. The experienced mass spectroscopist should also benefit from having all of the data collected together in one volume. This is a book to be used, rather than deposited in a library distant from the laboratory: we would hope that it will fmd a place on top of every mass spectrometer used for the analysis of priority pollutants.