This encyclopaedic catalogue of the pitfalls and problems that all analysts encounter in their work is destined to spend more time on the analyst's workbench than on a library shelf. The author has dedicated the book to ``the innumerable scientists who made mistakes, used impure chemicals and solvents, suffered the consequences of unanticipated side-reactions, and were otherwise exposed to mayhem yet were not too embarrassed to publish their findings''. Traditionally, the mass spectroscopist or gas chromatographer learnt his trade by participating in a 4-6 year apprenticeship as graduate student and post-doctoral researcher. Generally, no formal training was provided on the things that go wrong, but this information was accumulated by sharing in the experiences of colleagues. Nowadays, many novice scientists simply purchase a computerized instrument, plug it in, and use it. Much time can be wasted in studying and resolving problems due to artifacts and there is also a strong possibility that artifacts will not be recognized as such. For example, most analysts realize that they should use glass rather than plastic containers; but few of them would anticipate the possibility of plasticizer residues on glassware washed using detergent from a plastic bottle.This book is an easy-to-use compendium of problems encountered when using various commonly used analytical techniques. Emphasis is on impurities, by-products, contaminants and other artifacts. A separate entry is provided for each artifact. For specific chemicals, this entry provides the common name, mass spectrum, gas chromatographic data, CAS name and registry number, synonyms and a narrative discussion. More than 1100 entries are included. Mass spectral data are indexed in a 6-peak index (molecular ion, base peak, second peak, third peak) and there are also formula, author and subject indexes. An extensive bibliography contains complete literature citations.The book is designed to be used. It will not only allow experienced analysts to profit from the mistakes of others, but it will also be invaluable to other scientists who use analytical instruments in their work.