Spectrophotometric methods for the microdetermination of oxytetracycline and hostacycline

New, rapid and sensitive spectrophotometric methods have been developed for the determination of Oxytetracycline (OTC) and Hostacycline (HTC). The procedure is based on the observation that, OTC or HTC forms colored complexes with Zirconium (IV), the absorbance of which is proportional to the amount of tetracycline present. The variables affecting development of the color have been investigated and the conditions are optimized. Beer’s law is obeyed in the range 1.0-33.5 μg/ml for OTC and 4.0-40.0 μg/ml for HTC. The proposed methods can be employed for the analytical determination of Zirconium (IV). The corresponding Beer’s law ranges are 0.2-6.1 μg/ml with OTC and 0.5-7.3 μg/ml with HTC. Stoicheiometry of the complexes, regression parameters and relative standard deviation are reported for each of these determinations. The methods are successfully applied for the determination of OTC and HTC in pharmaceutical formulations and urine.