Improved estimation of the limit of detection in multivariate calibration

The limit of detection is one of the most important performance characteristics of an analytical procedure. This paper critically examines a recently introduced expression for estimating a multivariate limit of detection. The main result is that the proposed expression is inconsistent. An application from inductively coupled plasma - optical emission spectrometry (ICP-OES) shows that the true limit of detection may be overestimated by more than 20%. In addition, the practical evaluation of the proposed expression amounts to an iterative procedure, which is unattractive from an application point of view. A modification is derived that solves both problems. The relevant expressions are discussed with respect to their interpretability in terms of experimental design.