Scope of the book, and acknowledgements.- The articles are focused on 'real problems' in body-fluid analysis, typically with a final chromatographic separation of ~g or often ng amounts if the aim is quantitation. The pitfalls may not be realized by a typical chemist (cf. remarks in #A-3), but he may excel in metabolite iden- tification - which this book covers to a fair extent. Where identity is known, and the metabolite could interfere in therapeutic drug monitoring or in diagnosis or itself have clinical relevance, useful guidance will come from articles that follow. Authors have gone to much trouble, and are not to be blamed by any reader who would have liked an introduction to chromatography or to metabolic pathways (cf. list of conjugation reactions at end of concluding article). Appre- ciation is also expressed for permission to reproduce published mat- erial; the acknowledged sources include 1. Chroma tog. (Elsevier; e. g. in #A-l) , Anal. Chem. (American Chemical Society; #A-2) and Wiley.