Validation of qualitative analytical methods

Identificador:  TDX:782

Handle: https://hdl.handle.net/20.500.11797/TDX782

Autores:  Trullols Soler, Esther

Resumen:
The chemical information about the composition of a sample can be of different nature: which species are in the sample, their concentration or if they are structurally related, etc. In order to fit any of these requirements, either a qualitative or a quantitative analytical method may be used. If the aim is to identify species, a qualitative method will suit the problem at hand. These types of methods have been recently studied and nowadays are being increasingly used in several fields of analysis. For example, it is common to use qualitative methods as far as food analysis is concerned. On the contrary, if the aim is to quantify one or more analytes of a sample, a quantitative method will be very useful. This thesis has focused on qualitative analytical methods because they provide several advantages and they are being increasingly used. These types of methods can screen samples according to the presence or absence of certain analytes with regard to a pre-set level of concentration. That is to say, they are used as a step before the quantitative method and results in lower analysis time and costs because analyte quantification is not required in all situations. There are some particular analysis fields where qualitative methods are used as routine methods. Therefore, analyte quantification is not always necessary. Moreover, it is also important to provide reliable results, that is to say, to assure that the method performs with reliability. Any analytical method must have its requirements and its analytical properties previously defined, and their values must be proven. To confirm that the requirements and the analytical properties are the right ones and to confirm that they have the right values is to validate the analytical method. This is a necessary condition to use an analytical method. In this sense, the reliability of the results given to the clients or to the users is assured. Moreover, the ISO Standard 17025 strongly encourages method validation. Method validation has focused on quantitative methods. Therefore and as a result, there are more standards or guidelines addressed to quantitative methods validation. These guidelines are commonly used by several communities of practitioners. However, there is no generally accepted standard or validation procedure addressed to qualitative methods. In this sense, this thesis aims to contribute with the development of several validation procedures. The starting point is to provide an overview as a result of a bibliographic search concerning qualitative methods validation. This overview includes the criteria existing for qualitative methods classification as well as the institutions committed the validation of these methods. After that, a classification of these methods is suggested and the most relevant performance parameters in the validation process are defined. The subsequent practical applications describe the intrinsic characteristics of the corresponding qualitative analytical method. After that, the performance parameters that best fit the requirements and the characteristics of the method are defined and, finally, a validation strategy is proposed. Bear in mind, that the strategy considers the intrinsic characteristics of the analytical method. The overview including relevant aspects such as qualitative methods classification, performance parameters definitions and the institutions committed to qualitative method validation, among others, are presented as two publications included in the thesis. Regarding the three practical applications, they are presented as three accepted papers.