[Isoelectric focusing of an alkylating 3H-cyclophosphamide derivative from human bladder urine].

1. A stable polar 3H-cyclophosphamide metabolite capable of alkylating 4-(p-nitrobenzyl) pyridine and relatively high concentrated in human bladder urine was isolated. The compound has the pI value 9.06. It is a phosphoramide mustard conjugate. 2) Determination of the isoelectric point was accomplished by means of a new thin-layer isoelectric focusing technique applicable for characterizing loaded parts of low molecular weight substance mixtures.