RELATION BETWEEN FLUORESCENCE-SPECTRA OF DILUTE AND TURBID SAMPLES

We present a method to extend rank-annihilation-factor analysis (RAFA) for the analysis of fluorescence from homogeneous turbid samples. The method is based on a fundamental relationship between the fluorescenc e of a dilute solution and that of a turbid solution. We have derived this relationship, known as the transfer function, for turbid material s using the two-flux Kubelka-Munk theory. The method is tested with sp ectroscopic data from optically thin and turbid samples of the media o f a human aorta. At 450-nm excitation, agreement between the measured and predicted dilute-solution fluorescence spectra is within 5% at all emission wavelengths; at 340-nm excitation, agreement is within 20% a t all wavelengths, with some residual Soret-band absorption. The simul ations presented indicate that the transfer function is markedly more sensitive to absorption than to scattering properties.