Spectrofluorimetric determination of folic acid in tablets and urine samples using 1,10-phenanthroline-terbium probe

A new spectrofluorimetric method was reported for the determination of folic acid (FA), based on its quenching effect on the fluorescence intensity of Tb(3+) -1,10-phenanthroline complex as a fluorescent probe. The quenched fluorescence intensity at an emission wavelength of 545 nm was proportional to the concentration of FA in Tris-HCl buffer solution of pH 6.2. The effects of pH, time, order of addition of reagents, temperature and concentrations of Tb(3+) , buffer and 1,10-phenanthroline were investigated and optimized. The linear range for the determination of FA was 0.01-1.1 mg/L. The detection limit was 0.003 mg/L and the relative standard deviation for replicated determination of 1 mg/L of folic acid was 1.2%. This method was simple, practical and relatively free from interference effects. It was successfully applied to assess FA in pharmaceutical tablets and urine samples.