[Determination of propafenone in plasma by HPLC with direct isotope dilution (author's transl)].

A high performance liquid chromatography method based on the principle of direct isotope dilution is described for the determination of propafenone in plasma. With a sample volume of 2 ml and quantification by peak height measurements the lower limit of detection is about 2.5 micrograms/l, and the lower limit of determination about 10 micrograms/l. Values up to 250 micrograms/l are subject to a mean weighted relative error of 3.5%. At concentrations above 20 micrograms/l this method shows the same accuracy and reproducibility as the analytical procedure employing internal standardization with analogues. The method is made independent of possible storage losses by internal standardization of each sample immediately after withdrawal.