Application of Factorial Design for Optimization of Flow-Injection Spectrophotometric Determination of Tetracycline in Some Pharmaceutical Formulations


A simple and rapid flow injection (FI) spectrophotometric procedure for the determination of tetracycline (TC) has been developed. The method is based on the injection of 150 μl standard or sample solution into a distilled water carrier stream which merged at the merging zone with ferric nitrate solution with the optimum flow rate of 1.5 mL/min, subsequently the reaction will occur inside the reactor coil, forming brown color product that monitored at 418 nm. The flow injection experimental conditions were optimized by means of full factorial design. Under the optimum conditions, calibration graph was obtained over the range 2.0-120 μg/ml with a detection limit of 1.0 μg/ml. The correlation coefficient and molar absorptivity were 0.9994 and 4.343x103 L/ respectively. The results showed a good precision and accuracy. The method was successfully applied to the determination of tetracycline in pharmaceutical formulations and showed good agreement with those obtained by the standard method at 95% confidence level, with a sample throughput of 60/h.