ESTIMATION OF THE LIMIT OF DETECTION AND THE LIMIT OF DETERMINATION VIA CALIBRATION CURVE PROCEDURE .3. SELECTION OF THE FORTIFICATION LEVELS

The new DFG-approach (1991) for an estimation of the limit of detection and the limit of determination via calibration curve (DFG-Konzept ,,Ableitung von Nachweisgrenze und Bestimmungsgrenze nach dem Eichkurvenverfahren'', 1991) had been tested and proved to be applicable in the residue analysis of organochlorine pesticides, heavy metals, anabolics and chemotherapeutics3,4). In the present work, the influence of position and number of the fortification levels on the hight of the limit of detection and limit of estimation values, NG(DFG) and BG(DFG), is being evaluated. The calculations were carried out on the basis of simulated fortificaton data, as typically obtained in residue analysis. Each of the following measures: (1) broadening of the fortification interval by including more levels, (2) shifting the interval to higher concentrations, or (3) reducing the number of fortifications on each level, leads to a considerable increase of NG(DFG) and BG(DFG). Hints for planning and practical performance of the fortification experiments are given: (1) 4 concentration levels with 4 fortifications each should be selected, (2) the lowest fortification level corresponding to NG(sig6)), the highest to 10* NG(Sig). An English short version of the DFG-approach1) may be obtained from the author on request.