Fluorescence quenching studies on the interaction of riboflavin with tryptophan and its analytical application

Abstract

The ineraction between riboflavin (RBF) and tryptophan (Trp) was investigated using fluorescence spectroscopy and UV-vis absorption spectroscopy under physiological conditions. The fluorescence of Trp was quenched by RBF via dynamic quenching, which was analyzed using the Stern-Volmer relation. The value of the Forster distance R0 (2.31 nm) was obtained according to the Forster's theory of nonradiative energy transfer. Under physiological conditions, a linear relationship could be established between the quenched fluorescence intensity of Trp and the concentration of RBF in the range of 5.8 × 10(-7) -2.0 × 10(-5) mol/L. The detection limit was 1.8 × 10(-7) mol/L. The method was successfully applied to determine riboflavin concentrations in pharmaceutical samples.

Keywords: Forster theory; Stern-Volmer relation; dynamic quenching; nonradiative energy transfer; riboflavin; tryptophan.