Interaction of L-Tryptophan with Selected Important Ions in Aqueous Solution

Abstract

Effect of selected ions (Fe3+, Au3+, Al3+, Zn2+, Ni2+, Mg2+, Hg2+, Ca2+ and CN-) on fluorescence behavior of L-tryptophan was studied in aqueous solution. All the cations suppressed the fluorescence of L-tryptophan except CN- which caused an increase in the fluorescence of L-tryptophan. Fluorescence suppression were explained by the equation of Stern-Volmer which produced constants of Stern-Volmer (). and sensitivity was observed in the order Hg2+ > Au3+ > Fe3+ > Zn2+ > Ni2+ > Ca2+ > Al3+ > Mg2+. Detection and quantification threshold were calculated as 3 (S.D3) and 10 times of the standard deviation (10S.D) of the blank for twelve number of readings. was found between 6.8631104 and 0.1883104 M. Detection threshold (DT) was observed between 2.8710-7 – 6.38 10-6 while quantification threshold (QT) was observed between 9.58 10-7 and 2.13 10-5 mol L-1. In case of CN- a linear association between the enhancement in fluorescence intensity of L-tryptophan and CN- concentration was found between 0.00 -1.0x10-3 M. DT and QT were found in the order 2.710-5 and 9.0210-5 M respectively. The method is reproducible both for cations and anion and useful for their determination in the samples of the environment.