Evaluación del desempeño del método de ensayo de sulfatos en matrices de aguas claras en el Laboratorio de Control y Análisis de Alimentos LACONAL de la Universidad Técnica de Ambato.

Abstract

The validation of analytical methods is part of a process of improving the quality of laboratories, which aims to demonstrate with substantiated evidence and statistical basis that both the method used and the result of this analysis is accurate and provides reliable data within a working range defined by careful control of conditions, materials and equipment, in order to adapt procedures to routine working environment. So this leads to a formal recognition of the competence of the laboratory, that is the accreditation. On the other hand, control of water quality is of increasing interest, because of the extended use and massive consumption of this resource. Based on these criteria, the analytical method for the determination of sulfates in drinking and bottled purified water matrices, based on the turbidimetric technique, was validated, using as reference the procedure established in 4500-SO42- E Standard Methods for the Examination of Water and Wastewater 22nd ed. The reliability of the method to produce the expected outcome was cheked, by assessing linearity, sensitivity, precision, accuracy and by the calculation of its uncertainty. The developed method produces a linear response within the range of 5 to 50 mg/L with r2 of 0,9961and m of 0,0041, however, as the TULAS expose a maximum allowable limit of 250 mg SO42-/L, a working interval of 4,9 (LOQ) to 250 mg SO42-/L was established by dilution, with a percentage expanded uncertainty of 9,3% (p= 95.45%) and coefficients of variation of %CVr= 5,83 and %CVR= 5,85%, respectively, percentages accepted according to the criteria established by the coefficient of variation of Horwitz (%CVh), and with an average recovery percentage of 100 ± 6% (MRC: 25 mg/L).