Validação de métodos qualitativos: delineamento de procedimento e aplicação na pesquisa de resíduos de sulfonamidas em leite cru

Abstract

A detailed procedure for single-laboratory validation of qualitative methods was proposed to be employed as a basic reference in the organization of validation processes in food analysis laboratories. The experimental design and the selection of tools for data analysis were based on theoretical background, as well as aspects of efficiency, convenience and easiness. Four experimental stages were proposed, as follows: i) preliminary tests to determine the concentration range, ii) study of the rates, unreliability region, detection limit, acordance and concordance, iii) study of selectivity in presence of known interferences, and iv) study of robustness. The applicability of the procedure was demonstrated in the validation of a qualitative commercial kit for detection of residues of sulphonamides in raw milk, considering the visual and instrumental practices for reading the results. The validation indicated the importance of using appropriate and properly calibrated equipment for the reliability of results obtained in the instrumental reading. Despite the high sensitivity of the kit, the validation confirmed its suitability for the purpose of monitoring sulphonamides residues in raw milk, with reference to the limits of national and international legislations.