Validación de un método para determinar aceites y grasas en aguas por espectroscopia infrarroja

Abstract

This research project was developed with the aim of validating the method of oils and fats in water by infrared spectroscopy, for the AQLAB laboratory in the city of Francisco de Orellana. Reference method EPA 481.1, EPA 1664 (Validation method) was selected. Subsequently, the objectives for validation were established by proposing an experimental design at different concentrations of the analytes and finally the validation parameters were determined such as: Response function / Linearity, Selectivity / Specificity, Limit of detection, Limit of quantification, Precision (repeatability and / or reproducibility), Accuracy, Uncertainty, Work interval, considering as reference the NTE / ISO / IEC 17025: 2006 Standard. The results obtained in the validation demonstrated that the method used is suitable for statistical analysis. Performance criteria such as: coefficient of variation SDR (Standard Deviation) less than 15%, Accuracy (Recovery) of 70 to 120 % at all concentration levels, an uncertainty of U less than 30 % a confidence interval (K = 2), with a significance level of 95 % and a working interval of 0.3 to 70 mg / L were fully met, therefore, the method statement was accepted. It is concluded that the critical parameters of validation of oils and fats, in terms of the response function / linearity with a degree of adjustment. A coefficient of determination of 0.9969 was obtained, the percentage of the coefficient of variation is <15%, the percentage of recovery is from 70 to 105%, declaring an uncertainty of the method 28% and a working interval 0.11-914.41 mg / L due to samples of discharges from washing machines and lubricators containing high concentrations of oils and greases for this reason a very high range was obtained. It is recommended adjusting the calibration curves and check for interference.