[Quantitative determination of cyclophosphamide, ifosfamide, and trofosfamide and their stable metabolites on TLC-plates with the aid of 4-pyridine-aldehyde-2-benzothiazolyl-hydrazone (PBH) (author's transl)].

Cyclophosphamide, ifosfamide, and trofosfamide can be analysed quantitatively together with their stable alkylating urine metabolites on TL-plates by means of the PBH-reagent (4-pyridine-aldehyde-2-benzothiazolyl-hydrazone). The method requires only 0.01 ml urine, but a careful standardisation is necessary by using reference substances. The minimum measurable amounts are between 0.25 and 0.5 mug. In the urines of rat and man the carboxy derivatives and the dechloroethyl derivatives, respectively, resulting from side chain oxidation, are predominant next to cyclophosphamide, ifosfamide, or trofosfamide, respectively. Side chain oxidation can be prevalent, as we have found in some patients treated with ifosfamide. The method described allows not only the calculation of time functions for the excretion of PBH-reactive substances but also in vitro investigations of the chemokinetic properties of cyclophosphamide derivatives under physiological conditions.