Application of a special in-house validation procedure for environmental–analytical schemes including a comparison of functions for modelling the repeatability standard deviation

Abstract

For some years, a special in-house validation concept according to the Commission Decision 2002/657/EC of the European Union is employed. The validation concept is based on a variance component model, which allows to consider matrix- and operation-induced deviations and to calculate critical concentrations for given α-errors. The approach relies on a comprehensive mathematical model to asses simultaneously the in-house reproducibility and its components. One important component, the repeatability standard deviation, is estimated by means of a power function of the Horwitz-type. In this study, several performance characteristics were compared based on the use of four recommended estimations for the standard deviation depending on the concentration level of the analyte. A special factorial design for calibration, considering three factors influencing the variance of the measurement values, was applied for the determination of arsenic in surface water samples collected at several abandoned mining sites in Germany. The advantageous applicability of the validation method presented for analytical procedures referring to environmental tasks was demonstrated.