Validación de los Métodos de Determinación de Cromo Hexavalente y Sulfatos mediante Espectrofotometría UV-Visible en aguas del Distrito Metropolitano de Quito

Abstract

Due to the increase in the usage of analytical methods in water analysis and in order to obtain reliable results, validation of analytical methods is carried out. This guarantees that the final results obtained are accurate. The present project focuses on the validation of analytical methods to quantify hexavalent chromium and sulphates by using UV-visible spectrophotometry in natural waters of the Metropolitan District of Quito. For the development of the methods, fist the optimization was done to point where all the variables of the method were adjusted to obtain acceptable answers, then the validation was executed by monitoring several parameters such as: selectivity, linearity, range of work, limit of detection and quantification, accuracy, and uncertainty obtaining a veracity of 85% ≤% R≤ 115% for all levels of concentration in addition to a Repeatability coefficient of variation ≤5%, Reproducibility coefficient of Variation ≤5% and an uncertainty of less than 30% (k = 2) for all concentration levels. Once the validation was completed, the analytic methods were used in the 5 rivers that the Environment Secretariat monitors: Pita, San Pedro, Machángara, Guayllabamba, Monjas, as well as samples that arrive at the laboratory, where it was found that the amount of hexavalent chromium and sulphates is well below the current environmental regulations.