Influence of detection limit on the measured concentration distribution of trace elements

Abstract

AbstractThe concentration distributions of trace elements in large populations (n > 100) of biomedical samples were studied by x‐ray fluorescence spectrometry. For elements, the concentrations of which measured in all samples exceed the detection limit (DL) of the method, the log‐normal distribution was found to describe the data very well. For other elements, measured in only a fraction of the studied population, the observed distributions were truncated by the variable DL level. We demonstrate, however, that by using the information on the distribution of reported detection limits, the original distributions of concentration, and also the detection limits, can be reconstructed from the measured data. This can be done by solving the system of integral equations relating the measured and original distributions of the concentration and the detection limit. The applicability of this method is demonstrated in a comparative study of trace element concentrations in urine samples. Copyright © 2001 John Wiley & Sons, Ltd.