Book excerpt: Principles and Practices of Method Validation is an overview of the most recent approaches used for method validation in cases when a large number of analytes are determined from a single aliquot and where a large number of samples are to be analysed. Much of the content relates to the validation of new methods for pesticide residue analysis in foodstuffs and water but the principles can be applied to other similar fields of analysis. Different chromatographic methods are discussed, including estimation of various effects, eg. matrix-induced effects and the influence of the equipment set-up. The methods used for routine purposes and the validation of analytical data in the research and development environment are documented. The legislation covering the EU-Guidance on residue analytical methods, an extensive review of the existing in-house method validation documentation and guidelines for single-laboratory validation of analytical methods for trace-level concentrations of organic chemicals are also included. With contributions from experts in the field, any practising analyst dealing with method validation will find the examples presented in this book a useful source of technical information.