title: A diagnostic tool for determining the quality of accuracy validation. Assessing the method for determination of nitrate in drinking water.
abstract: Realistic internal validation of a method implies the performance validation experiments under intermediate precision conditions. The validation results can be organized in an X (NrxNs) (replicates x runs) data matrix, analysis of which enables assessment of the accuracy of the method. By means of Monte Carlo simulation, uncertainty in the estimates of bias and precision can be assessed. A bivariate plot is presented for assessing whether the uncertainty intervals for the bias (E +/- U(E)) and intermediate precision (RSDi +/- U(RSDi) are included in prefixed limits (requirements for the method). As a case study, a method for determining the concentration of nitrate in drinking water at the official level set by 98/83/EC Directive is assessed by use of the proposed plot.
authors.affiliation: Departamento de Química Analítica, Universitat de València, C/Vicente Andrés Estellés s/n, 46100, Burjassot, Valencia, Spain. sagrado@uv.es
authors.forename: L
authors.initials: L
authors.lastname: Escuder-Gilabert
authors.forename: E
authors.initials: E
authors.lastname: Bonet-Domingo
authors.forename: M J
authors.initials: MJ
authors.lastname: Medina-Hernández
authors.forename: S
authors.initials: S
authors.lastname: Sagrado
mesh_terms: D015982:Bias; D008722:Methods; D009010:Monte Carlo Method; D009573:Nitrites / Q000032:analysis*; D015203:Reproducibility of Results; D014867:Water / Q000032:analysis*; D014881:Water Supply / Q000592:standards
chemical_list: D009573:Nitrites; D014867:Water