DETECTION LIMIT AND ESTIMATE OF （检出限和估计的）.pdfVIP

THE RIGAKU JOURNAL VOL. 18 / NO.2 / 2001 DETECTION LIMIT AND ESTIMATE OF UNCERTAINTY OF ANALYTICAL XRF RESULTS* DR. RICHARD M. ROUSSEAU Geological Survey of Canada, 601 Booth St., Room 707, Ottawa, Ontario, K1A 0E8 Canada. e-mail: Rroussea@nrcan.gc.ca Some tools for estimating the uncertainty of XRF results are described. As introduction to the subject, the detection limit is treated even if this parameter and the uncertainty of a result describe different characteristics of an analytical method. The expression detection limit is probably one of the most widely misunderstood in XRF analysis. Not only is there a general lack of agreement about the order of magnitude of detection-limit data, but also the interna- tional convention for calculating such data is not always respected and the way of naming them is questionable. If a consensus exists on the meaning of this expression (the smallest amount of an analyte that can be detected in a specimen), the interpretation of data varies greatly. This paper attempts to suppress all this confusion. The basic philosophy behind the interpretation of the concept is reviewed and a new realistic and representative way to name it is proposed. The distinction between the limit of detection and the limit of determination is clearly established. General considerations for evaluating the uncertainty associated with the sample preparation are also discussed. Finally, a few comments on the way of reporting analytical results are presented. on the combination of errors introduced mainly by 1. Introduction the sample preparation, the measurement of both The basic requirement of quantitative X-ray peak and background intensities, the slope m of fluores