Abstract

• Nowadays, the testing and calibration laboratories have to provide high confidence and globally acceptable of measurement results in order to support the important action or decision based on it, especially for international trade and customer satisfaction. Therefore, according to guide ISO/IEC 17025, the measurements should be carried out by using validated method of analysis, defining the internal quality control procedures, participating in proficiency testing schemes and establishing the traceability and uncertainty of the measurement results. For this reason the determination of metals in drinking water requires the use of validated methods which demonstrating their robustness and reliability. In this context the estimate of uncertainty is an important tool allowing the identification the influence of each step of the analytical protocol in the overall quality of the results. In this paper, it was discussed the estimate of uncertainty during the measurement of metals (Cu, Zn and Fe) in proficiency test (PT) drinking water sample by atomic absorption spectrometry in flame mode. The concentration of Cu, Zn, Fe found in PT drinking water is 1.601 ± 0.043 mg/L, 1.061 ± 0.202 mg/L and 0.179 ± 0.095 mg/L respectively. The total uncertainty for Cu, Zn and Fe were 3%, 19%, 53% respectively.