Absorption and Fluorescence Spectra of Euchrysine Ggnx and Acridine Orange; Effects of Heparin, NaCl and a Cation Exchange Resin

The absorption and fluorescence spectra of two samples of dye labeled euchrysine were found to differ. One sample, labeled GGNX, had absorption and fluorescence maxima of 435 and 515 nanometers (nm) respectively. The other sample was not further labeled, but had absorption and fluorescence maxima of 492 and 535 nm. The latter values, as well as the shape of both the fluorescence and absorption curves of the second sample were superimposable on a recrystallized sample of acridine orange labeled correctly C. I. 46905. Euchrysine has two free amino groups which are fully methylated in acridine orange, therefore a nitrous acid test can differentiate the two dyes. The sample of euchrysine labeled GGNX gave a reaction, as did acridine yellow, C. I. 46025, but acridine orange, C. I. 46005, did not. Fluorescence metachromasy of euchrysine is less efficient than that of acridine orange in two ways: the shift in the spectrum is smaller by about 40 nm, making the separation of the colors more difficult both visually and by instruments and the metachromatic fluorescence has less than half of the intensity of acridine orange as measured at the peak for each dye. Confusion between these two dyes has occurred because suppliers have used the names interchangeably. For critical studies, the dye used should be identified by its Colour Index number.