The determination of aromatic amidines in plasma and urine.

Certain aromatic amidines have been reported to be useful chemotherapeutic agents for the treatment of leishmaniasis, trypanosomiasis, and babesiasis (1). Pharmacological and clinical studies of these compounds have been handicapped by lack of suitable methods for the determination of aromatic amidines in plasma and urine. Recently Fuller (2) described a method which is based upon a reaction between the aromatic amidines and glyoxal, a reaction which was studied first from the standpoint of preparative organic chemistry by Ekeley and Ronzio (3). Prior to the publication of the method of Fuller, we had occasion to develop a general procedure for the determination of aromatic amidines in body fluids.’ An attempt was made to apply the reaction with glyoxal alone (subsequently used by Fuller) under a variety of conditions. The reaction was difficult to control, and it did not appear promising for analytical purposes. However, a satisfactory procedure was developed by application of another reaction originally studied by Ekeley and Ronzio (4, 5) for preparation of glyoxalines; i.e., the reaction of aromatic amidines with glyoxal and benzaldehydc. This procedure is more sensitive than that of Fuller and is free of some of the difficulties reported for the latter method. The present method is more generally applicable, inasmuch as it yields fluorescent products with a wider range of aromatic amidines.