Procedures for Reference Material Selection and Use

Following RM certificate instructions for material usage and handling, incorporate the RM into the scheme of analysis at the earliest stage possible, i.e. prior to the beginning of sample decomposition. Take it through the entire analytical procedure at the same time and under the identical conditions as the actual analytical samples in order to correctly monitor all the sample manipulation and measurement steps. 

Results from the analysis of the RM and the certified value and their uncertainties are compared using simple statistical tests (Ihnat 1993,1998a). If the measured concentration value agrees with the certified value, the analyst can deduce with some confidence that the method is applicable to the analysis of materials of similar composition. If there is disagreement, the method as applied exhibits a bias and underlying causes of error should be sought and corrected, or their effects minimized. 

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