ASSESSMENT OF UNCERTAINTY OF ANALYTICAL RESULTS OF ATOMIC ABSORPTION SPECTROMETRY

Based on the guidelines given in ISO Guide 1993E,JJF standard and proposals described in literature,the uncertainty of analytical results of AAS was assessed according to two kinds of indexes of quantification,namely index Ⅰ and index Ⅱ.According to index Ⅰ,factors of sources of uncertainty arisen in the process of experimental manipulation were considered and expressed quantificationally,and on the basis of which,the overall uncertainty of the result was evaluated.The range of uncertainty obtained is usually rather narrow,and it is suitable for the judgement of the quality of analysis performed by the same analyst.According to the quantifying index Ⅱ,four key links in the analytical process,i.e.the calibration,the analysis of SRM and of unknoan sample and the control of analytical quality,were considered,and the factors of sources of uncertainty arisen in each of the links were expressed quantificationally.In this case,the range of uncertainty obtained is somewhat wider,and it is suitable to be used in the judgement of the quality of analysis performed by different analysts or laboratories.In practice,the indexes of quantification may be chosen according to the object to be assessed.