Terbium sensitized luminescence for the determination of fexofenadine in pharmaceutical formulations

A sensitive and specific luminescence method for the determination of Fexofenadine (FEX), in pharmaceutical formulations is reported. The method is based on the sensitization of terbium (Tb3+) by complex formation with FEX. The luminescence signal for Tb-FEX complex is greatly enhanced by the addition of triethylamine (ET3N) and zinc nitrate in methanol solution. Monitoring of the signal is accomplished when the instrument is in the phosphorescence mode with the excitation and emission wavelengths set at lambda(ex)= 220 nm and lambda(em)= 550 nm respectively. Optimum conditions for the formation of the complex in methanol were 2.25 x 10(-6) M of Tb3+, 5.00 x 10(-6) M of Et3N and Zn2+ which allows for the determination of 10-800 ppb of FEX in the batch mode with a detection limit of 0.3 ppb. The proposed method was successfully applied for the determination of FEX in pharmaceutical formulations. (C) 2015 The Authors. Published by Elsevier B.V. on behalf of King Saud University.