Binding of polyanions by biogenic amines. IV. Cadaverine, putrescine, histamine, spermidine and spermine complexes with oxalate, with particular reference to urine speciation.

The formation of oxalate - polyammonium cation (putrescine, cadaverine, his tamine, spermidine and spermine) complexes was studied by potentiometric (H +-glass electrode) measurements, at 25 and 37 degrees C. Experimental data give evidence of the formation of (ox) AH(r) species (diamines and spermidi ne, r = 1, 2, 3; spermine, r = 1...5) whose stability is comparable to that of other similar systems. The stability of different complexes is strictly dependent on charges involved in the formation reaction, and a mean contri bution for salt bridge (n) was calculated: -Delta G degrees = 7+/-1 kJ mol( -1) n(-1). The relevance of these complexes in the speciation of natural fl uids, and, in particular, of urine, was considered.