Abstract
With the ultimate purpose of evaluating the accuracy and specificity of the fluorescence of acridine orange stained cells or tissues as a sign of malignancy, this compound and its binding to stain receptors have been studied with biophysical methods. The present paper describes the identification of the lines in the proton magnetic resonance spectrum of acridine orange zinc trichloride. The ring proton lines are weak but the methyl line is strong and easy to record with a high ratio of the signal-to-background noise. The methyl line is composed of two superimposed parts, one narrow and one broad, with the same chemical shift. The reason why the methyl line is divided into components is, however, still unknown.