A STUDY OF THE RELATION BETWEEN THE LIMIT OF DETECTION AND THE LIMIT OF QUANTITATION IN INDUCTIVELY-COUPLED PLASMA SPECTROCHEMISTRY

The limit of quantitation based on a repeatability threshold concept i s compared with the limit of detection in induction coupled plasma ato mic emission spectrometry (ICP-AES) and induction coupled plasma mass spectrometry (ICP-MS). A 5%-based limit of quantitation would normally correspond to 10 times the 3-sigma based limit of detection. However, because of a possible lack of linearity of the calibration graph at l ow concentrations, some additional noise not taken into consideration and the possible use of time-correlated multichannel detection, this r atio of 10 cannot be used in every case. It is suggested that a suitab le way of determining the limit of quantitation is to establish the pl ot of the percentage relative standard deviation (RSD) of the net sign al as a function of the concentration in a range from the limit of det ection to 50 times this limit. (C) 1997 Elsevier Science B.V.