title: Uncertainty-based internal quality control. Harmonization considerations.
abstract: Three main quality aspects for analytical laboratories are internal method validation, internal quality control (IQC), and sample result uncertainty. Unfortunately, in the past they have been used in a nonharmonized way. The most universal IQC tool is the mean chart, but some criteria used to fix their control limits do not fit the real nature of analytical results. A new approach for fixing these limits is proposed (the u-approach). The key is the combined uncertainty, u, obtained from the method validation information, also used for estimating the sample result uncertainty. A comparative study on "in-control" simulated, bibliographic, and real laboratory data suggests that the u-approach is more reliable than other well-established criteria. In addition, the u-approach mean chart emerges as an IQC tool, consistent with chemical assays, which harmonizes the validation-control-uncertainty process.
authors.affiliation: Departamento de Química Analítica, Universitat de València, C/ Vicente Andrés Estellés s/n, E-46100 Burjassot, Valencia, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Bonet-Domingo
authors.forename: L
authors.initials: L
authors.lastname: Escuder-Gilabert
authors.forename: M J
authors.initials: MJ
authors.lastname: Medina-Hernandez
authors.forename: S
authors.initials: S
authors.lastname: Sagrado