Validación del método para determinar Pb, Cd, Ni por espectrometría de absorción atómica de llama en agua y suelo.

Abstract

The method for the determination of Lead, Cadmium and Nickel by atomic flame absorption spectrometry in water and soil matrices for the AQLAB laboratory in the city of Orellana was validated. The analytical need was established the laboratory against the demand of companies that require the determination of these parameters, in order to comply with national and local environmental ordinances. The standardized method for the analysis in Water and Soils SM 3030 B, 3111 B was selected, then the validation objectives were established and the experimental design was developed for each analyte (method set-up, validation data collection, Anova, calculation of uncertainty and statement of method). This was achieved under the fulfillment of internal procedures to the INEN Standard ISO IEC 17025.2006, as well as methodology related to the subject. The following requirements were analyzed: Selectivity / Specificity, Linearity / Response Function, Detection Limit, Limit of Quantification, Precision (Repeatability and / or Reproducibility), Accuracy, Uncertainty and Working Interval. It was demonstrated that the method is suitable for the intended application, by means of the statistical analysis the performance criteria were met such as: coefficient of variation of repeatability and reproducibility SDR <10%; Accuracy (Recovery) 85 to 115 % at all levels; Uncertainty U <33% of the lowest range with confidence interval (k=2), so that the validation metals in function-response linearity method, where the percentage of standard deviation is less than 10% percentage and recovery between 85 and 115%. Declaring an uncertainty of the method less than 33%. It is recommended to adjust the curves and calibration, and verify interference in the analysis.