[On the methodology of the determination of alkylating activities of nitrogen mustards with nitrobenzylpyridine (NBP) in biological material (author's transl)].

It is dealt with modifications to the spectrophotometric determination of the alkylating behaviour of bifunctional nitrogen mustards with 4-(4'-nitrobenzyl)pyridine (NBP). The authors succeeded in characterizing spectrophotometrically, by means of a one-phase procedure, not only soluble, but also difficultly soluble, therapeutically known and newly synthetized mustards in regard to their alkylating behaviour. In the framework of in vitro studies, the authors report of experimental details of the proper preparation of biological material for the determination of residual activities, the analytical approach being always depending on the structure of the respective mustard. The differences in the time courses of the acylating attacks in serum, blood and suspensions of leukaemic cells are demonstrated by the example of some selected nitrogen mustards.