Data Quality in Laboratories: Methods and Results for Soil, Foliar, and Water Chemical Analyses

Chemical analyses are an essential part of forest ecosystem monitoring activities. Harmonized, well-defined, and documented analytical methods are an important part of a laboratory Quality Control program and are essential to maximize spatial and temporal comparability of monitoring data. Different quality and data consistency checks, plausible ranges for analytical results, use of reference materials, and control charts are described for internal laboratory Quality Control. On the other side, coordinated ring tests among participating laboratories are an integral part of external Quality Control. Organization of ring tests, evaluation, and the benchmark with tolerable limits are described and specified. Results for water, foliage, and soil ring tests and the evaluation of quality indicators within the European forest ecosystem monitoring program are reported.