Problems of accuracy and precision in the determination of trace elements in water as shown by recent International Atomic Energy Agency intercomparison tests

Abstract

Results of a recent International Atomic Energy Agency intercomparison test on the determination of 16 trace elements in simulated fresh water samples are reported and discussed from the standpoint of accuracy and precision. Despite the considerable spread of results obtained from various laboratories, the over-all mean (after rejection of outliers) in most instances approximates closely to the true value. The importance of using sufficiently sensitive tests for the detection of outlying results is emphasised and the effectiveness of concurrent use of several criteria for that purpose is demonstrated. The relative frequency of employment of various analytical techniques is discussed and an attempt to compare their accuracy is presented.