During the past ten years a variety of methods involving mass spectrom­ etry have been developed for the analysis of environmentally important compounds. Much has been accomplished in that period to solve some of the important problems in the field. Growth of this methodology and its accomplishments has reached the point where an individual scientist can no longer have an in-depth knowledge of all the areas involved. We have attempted to provide this in-depth picture to those scientists concerned by having the important topics treated by experts in the subject matter. In order to provide all the relevant material in one volume we begin with the general topics which provide the basic background material necessary to understand the techniques discussed in the in-depth topics. These general chapters are kept brief, containing only the essentials needed by the working scientist to deal with the practical applications. References in these chapters are chosen to permit a more complete study of each chapter. The concept for this book was developed during the activities of two of the editors under a NATO travel grant. These editors gratefully acknowledge this support which made the initial planning of this book possible. The editors would like to thank the individual authors of each chapter for their cooperation and generously giving of their time for this project.