Principles of environmental analysis

This document is a revision to the ''Guidelines for Data Acquisition and Data Quality Evaluation in Environmental Chemistry''. The guidelines presented are organized according to a general operational model for conducting analytical measurements of environmental samples. Elements needed to obtain reliable data as well as factors that have been shown to produce unreliable measurements, are identified. The principles described include planning, quality assurance and quality control, verification and validation, precision and accuracy, sampling, measurements, and documentation and reporting. Differing degrees of reliability, dictated by the objectives, time, and resources available, influence the protocol chosen to meet the requirements of a given problem. Advances in analytical methodology continue to lower the concentration levels at which reliable measurements can be made, and requirements for increased sensitivity provide an incentive for advances in analytical procedures. 4 figures, 1 table.