Validación del método NMP para coliformes fecales en agua de consumo del laboratorio Ambienlab

Abstract

The objective of this titration work was to carry out the validation of the test method for the determination of fecal coliforms in drinking water. This validation was developed based on processes available in the third edition of 2017 of the test manual "Standard Methods" or SM (Translated into Spanish as Standardized Methods) for application in the private laboratory AMBIENLAB Cía. Ltda, located in the city of Quito, Ecuador. In order to ensure the quality and veracity of the results in the analysis of fecal coliforms for drinking water, this procedure followed the processes established in the ISO standard17025-2018 ("International Organization for Standardization") focused on testing and calibration laboratories. The methodology selected was SM 9221 B. Once the method has been selected, we proceed with the set-up of the method, the external calibration of the equipment and set the validation objectives to start with the experimental part that consists of two phases, a presumptive phase and a confirmatory phase. For its development, the criteria of performance, work interval and experimental design in conditions of repeatability and reproducibility were proposed. Analyte results were obtained through statistical treatment of ANOVA data. The validation objectives were established in accordance with current national regulations and experimental validation data provided by the AMBIENLAB laboratory. According to the results obtained, it was possible to demonstrate that the method is competently applicable in the laboratory; In addition, the validation objectives for the SM9221 B method were fully met, this means that the coefficient of repeatability and reproducibility are less than 5%, so it is recommended that the AMBIENLAB laboratory carry out the verification of the test method with certified reference material with a monthly frequency at least at a concentration level to ensure the quality of the results obtained.