Repositori URV

Identifier: TDX:755

Handle: https://hdl.handle.net/20.500.11797/TDX755

Authors:
Boqué Martí, Ricard

Abstract:
Limits of detection in multivariate analysisInternational norms concerning the quality of analytical laboratories establish that an analytical method, before being used as a routine method, has to be validated. Validation is defined as the process of verifying that a method is fit for purpose, that is, suitable for its intended use. Among the important performance parameters in method validation, there is the limit of detection (LOD).Analytical methods that use techniques capable of generating multivariate data are more and more frequent. It is therefore important to derive their associated performance parameters. In this Doctoral Thesis we have focused on the study of the LODs. In the first chapter, the historical evolution of the concept of LOD is presented, together with the different approaches to calculate it in analytical methods using univariate calibration. The different factors affecting the calculation of the LOD are also described.. The different existing techniques of multivariate analysis, together with the various mathematical models used, have motivated the development of different approaches for calculating multivariate LODs. In the second chapter all the approaches developed so far are critically reviewed. In chapter 3 an approach is presented to calculate the LOD to data obtained from a hyphenated technique, gas chromatography-mass spectrometry. The approach is based on the use of the calibration line of the scores of the first principal component (obtained by principal component analysis decomposition of the original response matrix) versus the concentrations of the calibration standards. This approach is only applicable if interfering substances are not present and when the first principal component explains a very high percentage of the information