Abstract

Within the ALADIN project (EU project Nr. GTC1-2000-28005) the stability of 17ß-methyl-5ß-androst-1-ene-3α,17α-diol (epimetendiol, EMD) and of clenbuterol in urine at 4°C, -20°C and –80°C was to test for at least 2 years. The concentrations were determined by means of calibration curves with a working range from 0.5 to 5.0 ng/ml following the DIN 38 402 Part 51. Ten calibration urine samples were prepared by adding 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 µl of the EMD working solution while clenbuterol was added from 10 different working solutions which were prepared by dilution of 10 different stock solutions. To investigate the influence of the different preparatory steps on the uncertainty the standard deviations of the method for EMD and clenbuterol are used. When reference substances for calibration are very expensive or available only in small amounts calibrators are usually prepared from one solution. In such cases the uncertainty has to be extended. The data presented here shows that the normally applied multiplication with a factor 2 is sufficient to compensate for the lack of independence of the calibrators. Aus dem Text