On the assessment of compliance with legal limits - Part 1: Signal and concentration domains

Taking into account the uncertainty of measurement when assessing compliance of a given sample with compositional specifications or statutory limits is an open question. Rigorous assessment should be performed within the signal domain, and by considering both alpha and beta errors. Working within the concentration domain through a calibration function, which is affected by additional experimental uncertainties, involves a different degree of uncertainty and can sometimes lead to unreliable verdicts. The matter is discussed, and illustrated with the aid of some worked examples, each using multiple simulated data sets, obtained by adding an arbitrarily chosen Gaussian noise to representative response/concentration functional relationships.