FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF TETRACYCLINE ANTIBIOTICS

The determination of the tetracycline antibiotics doxycycline, oxytetracycline, rolitetracycline and tetracycline using a flow-injection method with spectrophotometric detection based on their reaction with 4-aminophenazone and hencyanoferrate(III) is described. The flow-injection system was optimized using a modified simplex method and the results were compared with those from a univariate procedure of optimization. Under the optimized conditions, the determination of the tetracyclines in the ranges 1-20 and 20-250 mg l-1 with a relative standard deviation of less-than-or-equal-to 1% for 10 and 100 mg l-1, respectively (n = 10), and a sample throughput of 60-70 h-1 was achieved. The method was applied to the determination of tetracyclines in pharmaceutical preparations.